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Preconceptional Folate Supplementation and the Risk of Spontaneous Preterm Birth: A Cohort Study
Bukowski, Radek
Malone, Fergal D.
Porter, Flint T.
Nyberg, David A.
Comstock, Christine H.
Hankins, Gary D. V.
Eddleman, Keith
Gross, Susan J.
Dugoff, Lorraine
Craigo, Sabrina D.
Timor-Tritsch, Ilan E.
Carr, Stephen R.
Wolfe, Honor M.
D'Alton, Mary E.
PLoS Medicine
In an analysis of a cohort of pregnant women, Radek Bukowski and colleagues describe an association between taking folic acid supplements and a reduction in the risk of preterm birth.
Low plasma folate concentrations in pregnancy are associated with preterm birth. Here we show an association between preconceptional folate supplementation and the risk of spontaneous preterm birth.
Methods and Findings
In a cohort of 34,480 low-risk singleton pregnancies enrolled in a study of aneuploidy risk, preconceptional folate supplementation was prospectively recorded in the first trimester of pregnancy. Duration of pregnancy was estimated based on first trimester ultrasound examination. Natural length of pregnancy was defined as gestational age at delivery in pregnancies with no medical or obstetrical complications that may have constituted an indication for delivery. Spontaneous preterm birth was defined as duration of pregnancy between 20 and 37 wk without those complications. The association between preconceptional folate supplementation and the risk of spontaneous preterm birth was evaluated using survival analysis. Comparing to no supplementation, preconceptional folate supplementation for 1 y or longer was associated with a 70% decrease in the risk of spontaneous preterm delivery between 20 and 28 wk (41 [0.27%] versus 4 [0.04%] spontaneous preterm births, respectively; HR 0.22, 95% confidence interval [CI] 0.08–0.61, p = 0.004) and a 50% decrease in the risk of spontaneous preterm delivery between 28 and 32 wk (58 [0.38%] versus 12 [0.18%] preterm birth, respectively; HR 0.45, 95% CI 0.24–0.83, p = 0.010). Adjustment for maternal characteristics age, race, body mass index, education, marital status, smoking, parity, and history of prior preterm birth did not have a material effect on the association between folate supplementation for 1 y or longer and spontaneous preterm birth between 20 and 28, and 28 to 32 wk (adjusted HR 0.31, 95% CI 0.11–0.90, p = 0.031 and 0.53, 0.28–0.99, p = 0.046, respectively). Preconceptional folate supplementation was not significantly associated with the risk of spontaneous preterm birth beyond 32 wk. The association between shorter duration (<1 y) of preconceptional folate supplementation and the risk of spontaneous preterm birth was not significant after adjustment for maternal characteristics. However, the risk of spontaneous preterm birth decreased with the duration of preconceptional folate supplementation (test for trend of survivor functions, p = 0.01) and was the lowest in women who used folate supplementation for 1 y or longer. There was also no significant association with other complications of pregnancy studied after adjustment for maternal characteristics.
Preconceptional folate supplementation is associated with a 50%–70% reduction in the incidence of early spontaneous preterm birth. The risk of early spontaneous preterm birth is inversely proportional to the duration of preconceptional folate supplementation. Preconceptional folate supplementation was specifically related to early spontaneous preterm birth and not associated with other complications of pregnancy.
Editors' Summary
Most pregnancies last about 40 weeks, but sometimes the new family member arrives early. Every year, half a million babies in the United States (12.5% of all babies) are born prematurely (before 37 completed weeks of pregnancy). Sadly, premature babies are more likely to die than full-term babies and many have short- and/or long-term health problems. Premature babies often have breathing problems, they are susceptible to life-threatening infections, and they are more likely to have learning and developmental disabilities than those born on time. The severity of these health problems depends on the degree of prematurity—preterm babies born between 34 and 36 weeks of pregnancy rarely develop severe disabilities, but a quarter of babies born before 28 weeks of pregnancy develop serious lasting disabilities and half have learning and behavioral problems. Although doctors have identified some risk factors for early delivery (for example, smoking), it is impossible to predict who will have an early birth and there is no effective way to prevent preterm births.
Why Was This Study Done?
Some researchers think that folate supplements may prevent preterm births. Folate (folic acid), a vitamin found in leafy green vegetables, fruits, and dried beans, helps to prevent neural tube birth defects. Consequently, women are encouraged to take folic acid supplements throughout (and preferably before) pregnancy and many governments now mandate that bread, pasta, and other grain products be fortified with folic acid to help women get sufficient folate. There is some evidence that women who deliver early have less folate in their blood than women who deliver at term. Furthermore, folate supplementation during pregnancy has increased the length of pregnancy in some but not all clinical trials. A possible explanation for these mixed results is that the duration of pregnancy reflects conditions in the earliest stages of pregnancy or before conception and that folate supplementation needs to start before conception to reduce the risk of preterm birth. In this study, the researchers test this idea by analyzing data collected from nearly 35,000 pregnant women enrolled in a study that was originally designed to investigate screening for Down's syndrome.
What Did the Researchers Do and Find?
During the first three months of their pregnancy, the women were asked whether they had taken folate supplements before conception. The duration of each pregnancy was estimated from ultrasound measurements taken early in the pregnancy and from the time of delivery. During the study, 1,658 women had spontaneous preterm deliveries before 37 weeks and 160 delivered before 32 weeks. After allowing for other maternal characteristics that might have affected the likelihood of preterm delivery, the risk of spontaneous preterm delivery between 20 and 28 weeks was 70% lower in women who took folate supplements for more than a year before becoming pregnant than in women who didn't take a supplement. Long-term folate supplementation also reduced the risk of preterm delivery between 28 and 32 weeks by 50% but did not affect the risk of preterm birth beyond 32 weeks. Folate supplementation for less than a year before conception did not reduce the risk of preterm birth, and folate supplementation was not associated with any other complications of pregnancy.
What Do These Findings Mean?
These findings show that folate supplementation for a year or more before conception is associated with a 50%–70% decrease in early (but not late) spontaneous preterm births and that the longer a woman takes folate supplements before becoming pregnant, the lower her risk of a preterm birth. Although the researchers allowed for maternal characteristics that might have affected the duration of pregnancy, it is possible that folate supplementation may not be responsible for the reduction in preterm birth risk seen in this study. For example, taking folate supplements may be a marker of healthy behavior and the women taking the supplements might have been doing something else that was reducing their risk of preterm birth. However, despite this and other limitations of this study, these findings suggest that long-term folate supplementation before conception is worth investigating further as a potential way to prevent preterm births.
Additional Information
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1000061.
This study is further discussed in a PLoS Medicine Perspective by Nicholas Fisk
The MedlinePlus encyclopedia contains a page on premature babies (in English and Spanish); MedlinePlus provides links to other information on premature babies (in English and Spanish)
The US National Institute of Child Health and Human Development provides information on preterm labor and birth
The March of Dimes, a nonprofit organization for pregnancy and baby health, provides information on preterm birth and on folic acid (in English and Spanish)
The Nemours Foundation, another nonprofit organization for child health, also provides information on premature babies (in English and Spanish)
The US Office of Dietary Supplements has a fact sheet on folate
Related Articles
The Effect of Intermittent Antenatal Iron Supplementation on Maternal and Infant Outcomes in Rural Viet Nam: A Cluster Randomised Trial
Hanieh, Sarah
Ha, Tran T.
Simpson, Julie A.
Casey, Gerard J.
Khuong, Nguyen C.
Thoang, Dang D.
Thuy, Tran T.
Pasricha, Sant-Rayn
Tran, Thach D.
Tuan, Tran
Dwyer, Terence
Fisher, Jane
Biggs, Beverley-Ann
PLoS Medicine
Beverley-Anne Biggs and colleagues conduct a community-based cluster randomized trial in rural Viet Nam to compare the effect of antenatal iron-folic acid supplementation taken daily or twice weekly on maternal and infant outcomes.
Please see later in the article for the Editors' Summary
Anemia affects over 500 million women, and in pregnancy is associated with impaired maternal and infant outcomes. Intermittent antenatal iron supplementation is an attractive alternative to daily dosing; however, the impact of this strategy on infant outcomes remains unclear. We compared the effect of intermittent antenatal iron supplementation with daily iron supplementation on maternal and infant outcomes in rural Viet Nam.
Methods and Findings
This cluster randomised trial was conducted in Ha Nam province, Viet Nam. 1,258 pregnant women (<16 wk gestation) in 104 communes were assigned to daily iron–folic acid (IFA), twice weekly IFA, or twice weekly multiple micronutrient (MMN) supplementation. Primary outcome was birth weight. Mean birth weight was 3,148 g (standard deviation 416). There was no difference in the birth weights of infants of women receiving twice weekly IFA compared to daily IFA (mean difference [MD] 28 g; 95% CI −22 to 78), or twice weekly MMN compared to daily IFA (MD −36.8 g; 95% CI −82 to 8.2). At 32 wk gestation, maternal ferritin was lower in women receiving twice weekly IFA compared to daily IFA (geometric mean ratio 0.73; 95% CI 0.67 to 0.80), and in women receiving twice weekly MMN compared to daily IFA (geometric mean ratio 0.62; 95% CI 0.57 to 0.68), but there was no difference in hemoglobin levels. Infants of mothers who received twice weekly IFA had higher cognitive scores at 6 mo of age compared to those who received daily IFA (MD 1.89; 95% CI 0.23 to 3.56).
Twice weekly antenatal IFA or MMN did not produce a clinically important difference in birth weight, when compared to daily IFA supplementation. The significant improvement in infant cognitive outcomes at 6 mo of age following twice weekly antenatal IFA requires further exploration, and provides additional support for the use of intermittent, rather than daily, antenatal IFA in populations with low rates of iron deficiency.
Trial registration
Australia New Zealand Clinical Trials Registry 12610000944033
Please see later in the article for the Editors' Summary
Editors' Summary
Anemia is a common condition in which the blood does not supply the body with enough oxygen because of a low number of red blood cells or low levels of hemoglobin—the iron-containing pigment that enables red blood cells to carry oxygen. Iron deficiency is the most common cause of anemia worldwide and, according to the World Health Organization, affects over 2 billion people: half of all pregnant women and 40% of preschool children in low- and middle-income countries are thought to be anemic. Anemia contributes to 20% of all maternal deaths and is also linked to increased maternal morbidity, higher rates of preterm birth and low birth weight, and reduced infant survival, with potential long-term consequences for child growth and development. Identifying and treating iron deficiency anemia is therefore a global health priority.
Why Was This Study Done?
Daily iron–folic acid supplementation given from early in pregnancy is the standard recommended approach to prevent and treat anemia in pregnant women, but recently the World Health Organization recommended intermittent use because of poor compliance with daily regimes (because of side effects) and poor bowel absorption. However, the evidence from many of the studies used to support this recommendation was of poor quality, and so it remains unclear whether intermittent supplementation is as, or more, effective than daily supplementation, especially in lower income settings where antenatal testing for anemia is not readily available. So in this study, the researchers conducted a community-based cluster randomized trial (where groups of people are randomized, rather than individuals) in rural Viet Nam to compare the effect of antenatal iron–folic acid supplementation taken twice weekly (either alone, or in combination with other micronutrients) with daily iron–folic acid supplementation, on maternal and infant outcomes during the first six months of life.
What Did the Researchers Do and Find?
The researchers randomized 104 communes in Ha Nam Province, Viet Nam, and enrolled 1,258 women who were less than 16 weeks pregnant into the study between September and November 2010. Although the researchers intended to register the trial before the study started, registration was delayed by a month because the supplements arrived earlier than the researchers anticipated, and they thought it best to start recruiting at that time to avoid the Vietnamese New Year, when women might be travelling. Each woman was interviewed and had blood taken for hemoglobin and iron indices (ferritin) before receiving daily iron–folic acid supplementation (426 women), twice weekly iron–folic acid supplementation (425 women), or twice weekly iron–folic acid supplementation plus micronutrients (407 women). The women had follow-up assessments at 32 weeks gestation, delivery, and at six months postpartum: their infants were assessed at birth and at six months old.
The researchers found that at enrollment, the women's average hemoglobin concentration was 123 g/l, and 12.6% of the women were anemic. At 32 weeks gestation, 10.8% of the women were anemic, but there was no difference in hemoglobin levels between the three supplement groups. The average ferritin level was 75.6 µg/l at enrollment, with 2.2% of women iron deficient. Ferritin levels decreased from enrollment to 32 weeks gestation in all supplement groups but were lower in women who took twice weekly supplements. The researchers also found that birth weight (the primary outcome) was similar in all supplement groups, and there were also no differences in gestational age or in the risk of prematurity, stillbirth, or early neonatal death. At six months, there were also no differences in the levels of infant hemoglobin, prevalence of anemia, or growth rates. However, infants born to mothers in the twice weekly iron–folic acid group had improved cognitive development compared to infants born to mothers in the daily supplement group. Finally, the researchers found that adherence rates were significantly higher in the twice weekly iron–folic acid supplement group compared to the once daily regime.
What Do These Findings Mean?
These findings suggest that in an area of Southeast Asia with low anemia prevalence, once daily antenatal supplementation with iron–folic acid did not provide any benefits in birth weight or improved infant growth over twice weekly supplementation. Furthermore, twice weekly supplementation with iron–folic acid was associated with improved maternal adherence rates and also improved cognitive development in infants aged six months—a finding that requires further study and provides added support for the use of intermittent iron–folic acid supplementation over daily supplementation.
Additional Information
Please access these websites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001470.
The World Health Organization website has comprehensive information on anemia, including a report of global estimates and the guideline Intermittent Iron and Folic Acid Supplementation in Non-Anaemic Pregnant Women
Wikipedia provides information on iron supplementation (note: Wikipedia is a free online encyclopedia that anyone can edit; available in several languages)
Related Articles
Risk of pre-eclampsia in first and subsequent pregnancies: prospective cohort study
Hernández-Díaz, Sonia
Toh, Sengwee
Cnattingius, Sven
BMJ : British Medical Journal
Objective To investigate whether pre-eclampsia is more common in first pregnancies solely because fewer affected women, who presumably have a higher risk of recurrence, go on to have subsequent pregnancies.
Design Prospective cohort study.
Setting Swedish Medical Birth Register.
Participants 763 795 primiparous mothers who had their first births in Sweden, 1987-2004.
Main outcome measures Pre-eclampsia.
Results The risk of pre-eclampsia was 4.1% in the first pregnancy and 1.7% in later pregnancies overall. However, the risk was 14.7% in the second pregnancy for women who had had pre-eclampsia in their first pregnancy and 31.9% for women who had had pre-eclampsia in the previous two pregnancies. The risk for multiparous women without a history of pre-eclampsia was around 1%. The incidence of pre-eclampsia associated with delivery before 34 weeks' gestation was 0.42% in primiparous women, 0.11% in multiparous women without a history of pre-eclampsia, and 6.8% and 12.5% in women who had had one or two previous pregnancies affected, respectively. The proportion of women who went on to have a further pregnancy was 4-5% lower after having a pregnancy with any pre-eclampsia but over 10% lower if pre-eclampsia was associated with very preterm delivery. The estimated risk of pre-eclampsia in parous women did not change with standardisation for pregnancy rates.
Conclusions Having pre-eclampsia in one pregnancy is a poor predictor of subsequent pregnancy but a strong predictor for recurrence of pre-eclampsia in future gestations. The lower overall risk of pre-eclampsia among parous women was not explained by fewer conceptions among women who had had pre-eclampsia in a previous gestation. Early onset pre-eclampsia might be associated with a reduced likelihood of a future pregnancy and with more recurrences than late onset pre-eclampsia when there are further pregnancies. Findings are consistent with the existence of two distinct conditions: a severe recurrent early onset type affected by chronic factors, genetic or environmental, and a milder sporadic form affected by transient factors.
Related Articles
The effects of vitamin C supplementation on pre-eclampsia in Mulago Hospital, Kampala, Uganda: a randomized placebo controlled clinical trial
Kiondo, Paul
Wamuyu-Maina, Gakenia
Wandabwa, Julius
Bimenya, Gabriel S
Tumwesigye, Nazarius Mbona
Okong, Pius
BMC Pregnancy and Childbirth
Oxidative stress plays a role in the pathogenesis of pre-eclampsia. Supplementing women with antioxidants during pregnancy may reduce oxidative stress and thereby prevent or delay the onset pre-eclampsia. The objective of this study was to evaluate the effect of supplementing vitamin C in pregnancy on the incidence of pre-eclampsia, at Mulago hospital, Kampala, Uganda.
This was a (parallel, balanced randomization, 1:1) placebo randomized controlled trial conducted at Mulago hospital, Department of Obstetrics and Gynecology. Participants included in this study were pregnant women aged 15-42 years, who lived 15 km or less from the hospital with gestational ages between 12-22 weeks. The women were randomized to take 1000mg of vitamin C (as ascorbic acid) or a placebo daily until they delivered. The primary outcome was pre-eclamsia. Secondary outcomes were: severe pre-eclampsia, gestational hypertension, preterm delivery, low birth weight and still birth delivery. Participants were 932 pregnant women randomized into one of the two treatment arms in a ratio of 1:1. The participants, the care providers and those assessing the outcomes were blinded to the study allocation.
Of the 932 women recruited; 466 were randomized to the vitamin and 466 to the placebo group. Recruitment of participants was from November 2011 to June 2012 and follow up was up to January 2013. Outcome data was available 415 women in the vitamin group and 418 women in the placebo group.
There were no differences in vitamin and placebo groups in the incidence of pre-eclampsia (3.1% versus 4.1%; RR 0.77; 95% CI: 0.37-1.56), severe pre-eclampsia (1.2% versus 1.0%; RR 1.25; 95% CI: 0.34-4.65), gestational hypertension(7.7% versus 11.5%; RR 0.67; 95% CI: 0.43-1.03), preterm delivery (11.3% versus 12.2%; RR 0.92; 95% CI: 0.63-1.34), low birth weight (11.1% versus 10.3%; RR 1.07; 95% CI: 0.72-1.59) and still birth delivery (4.6% versus 4.5%; RR 1.01; 95% CI: 0.54-1.87).
Supplementation with vitamin C did not reduce the incidence of pre-eclampsia nor did it reduce the adverse maternal or neonatal outcomes. We do not recommend the use of vitamin C in pregnancy to prevent pre-eclampsia.
Trial registration
This study was registered at the Pan African Clinical Trial Registry, PACTR201210000418271 on 25th October 2012.
Related Articles
The Effect of Changing Patterns of Obstetric Care in Scotland (1980–2004) on Rates of Preterm Birth and Its Neonatal Consequences: Perinatal Database Study
Norman, Jane E.
Morris, Carole
Chalmers, James
PLoS Medicine
Jane Norman and colleagues analyzed linked perinatal surveillance data in Scotland and find that between 1980 and 2004 increases in spontaneous and medically induced preterm births contributed equally to the rising rate of preterm births.
Rates of preterm birth are rising worldwide. Studies from the United States and Latin America suggest that much of this rise relates to increased rates of medically indicated preterm birth. In contrast, European and Australian data suggest that increases in spontaneous preterm labour also play a role. We aimed, in a population-based database of 5 million people, to determine the temporal trends and obstetric antecedents of singleton preterm birth and its associated neonatal mortality and morbidity for the period 1980–2004.
Methods and Findings
There were 1.49 million births in Scotland over the study period, of which 5.8% were preterm. We found a percentage increase in crude rates of both spontaneous preterm birth per 1,000 singleton births (10.7%, p<0.01) and medically indicated preterm births (41.2%, p<0.01), which persisted when adjusted for maternal age at delivery. The greater proportion of spontaneous preterm births meant that the absolute increase in rates of preterm birth in each category were similar. Of specific maternal complications, essential and pregnancy-induced hypertension, pre-eclampsia, and placenta praevia played a decreasing role in preterm birth over the study period, with gestational and pre-existing diabetes playing an increasing role. There was a decline in stillbirth, neonatal, and extended perinatal mortality associated with preterm birth at all gestation over the study period but an increase in the rate of prolonged hospital stay for the neonate. Neonatal mortality improved in all subgroups, regardless of obstetric antecedent of preterm birth or gestational age. In the 28 wk and greater gestational groups we found a reduction in stillbirths and extended perinatal mortality for medically induced but not spontaneous preterm births (in the absence of maternal complications) although at the expense of a longer stay in neonatal intensive care. This improvement in stillbirth and neonatal mortality supports the decision making behind the 34% increase in elective/induced preterm birth in these women. Although improvements in neonatal outcomes overall are welcome, preterm birth still accounts for over 66% of singleton stillbirths, 65% of singleton neonatal deaths, and 67% of infants whose stay in the neonatal unit is "prolonged," suggesting this condition remains a significant contributor to perinatal mortality and morbidity.
In our population, increases in spontaneous and medically induced preterm births have made equal contributions to the rising rate of preterm birth. Despite improvements in related perinatal mortality, preterm birth remains a major obstetric and neonatal problem, and its frequency is increasing.
Please see later in the article for the Editors' Summary
Editors' Summary
Most pregnancies last about 40 weeks but increasing numbers of babies are being born preterm, before they reach 37 weeks of gestation (gestation is the period during which a baby develops in its mother). Nowadays in the US, for example, more than half a million babies arrive earlier than expected every year (1 in 8 babies). Although improvements in the care of newborn babies (neonatal care) mean that preterm babies are more likely to survive than in the past, preterm birth remains the single biggest cause of infant death in many developed countries, and many preterm babies who survive have long-term health problems and disabilities, particularly those born before 32 weeks of gestation. Preterm births can be spontaneous or medically induced. At present, it impossible to predict which mothers will spontaneously deliver early and there is no effective way to prevent these preterm births; medically induced early labor is undertaken when either the unborn baby or mother would be at risk if the pregnancy continued to full term.
Why Was This Study Done?
Preterm birth rates need to be reduced, but before this can be done it is important to know how the causes of preterm birth, the numbers of preterm stillbirths, and the numbers of preterm babies who die at birth (neonatal deaths) or soon after (perinatal deaths) are changing with time. If, for example, the rise in preterm births is mainly due to an increase in medically induced labor and if this change in practice has reduced neonatal deaths, it would be unwise to try to reduce the preterm birth rate by discouraging medically induced preterm births. So far, data from the US and Latin America suggest that the increase in preterm births in these countries is solely due to increased rates of medically induced preterm births. However, in Europe and Australia, the rate of spontaneous preterm births also seems to be increasing. In this study, the researchers examine the trends over time and causes of preterm birth and of neonatal death and illness in Scotland over a 25-year period.
What Did the Researchers Do and Find?
By searching a Scottish database of linked maternity records and infant health and death records, the researchers identified 1.49 million singleton births that occurred between 1980 and 2004 of which nearly 90,000 were preterm births. Over the study period, the rates of spontaneous and of medically induced preterm births per 1,000 births increased by 10.7% and 41.2%, respectively, but because there were more spontaneous preterm births than medically induced preterm births, the absolute increase in the rates of each type of birth was similar. Several maternal complications including preeclampsia (a condition that causes high blood pressure) and placenta previa (covering of the opening of the cervix by the placenta) played a decreasing role in preterm births over the study period, whereas gestational and preexisting diabetes played an increasing role. Finally, there was a decline in stillbirths and in neonatal and perinatal deaths among preterm babies, although more babies remained in the hospital longer than 7 days after birth. More specifically, after 28 weeks of gestation, stillbirths and perinatal deaths decreased among medically induced preterm births but not among spontaneous preterm births.
What Do These Findings Mean?
These findings indicate that in Scotland between 1980 and 2004, increases in spontaneous and medically induced preterm births contributed equally to the rising rate of preterm births. Importantly, they also show that the increase in induced preterm births helped to reduce stillbirths and neonatal and perinatal deaths, a finding that supports the criteria that clinicians currently use to decide whether to induce an early birth. Nevertheless, preterm births still account for two-thirds of all stillbirths, neonatal deaths, and extended neonatal stays in hospital and thus cause considerable suffering and greatly increase the workload in neonatal units. The rates of such births consequently need to be reduced and, for Scotland at least, ways will have to be found to reduce the rates of both spontaneous and induced preterm births to achieve this goal while continuing to identify those sick babies who need to be delivered early to give them the best chance of survival.
Additional Information
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1000153
Tommys is a nonprofit organization that funds research and provides information on the causes and prevention of miscarriage, premature birth, and stillbirth
The March of Dimes, a nonprofit organization for pregnancy and baby health, provides information on preterm birth (in English and Spanish)
The Nemours Foundation, another nonprofit organization for child health, also provides information on premature babies (in English and Spanish)
The US Centers for Disease Control and Prevention provides information on maternal and infant health (in English and Spanish)
The US National Women's Health Information Center has detailed information about pregnancy, including a section on pregnancy complications
MedlinePlus provides links to other information on premature babies and to information on pregnancy (in English and Spanish)
Related Articles
Pre-eclampsia, eclampsia, and hypertension
Duley, Lelia
Clinical Evidence
Pre-eclampsia (raised blood pressure and proteinuria) complicates 2% to 8% of pregnancies, and increases morbidity and mortality in the mother and child. Pre-eclampsia is more common in women with multiple pregnancy and in those who have conditions associated with microvascular disease.
Methods and outcomes
We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of preventive interventions in women at risk of pre-eclampsia? What are the effects of interventions in women who develop mild to moderate hypertension during pregnancy? What are the effects of interventions in women who develop severe pre-eclampsia or very high blood pressure during pregnancy? What is the best choice of anticonvulsant for women with eclampsia? We searched: Medline, Embase, The Cochrane Library, and other important databases up to February 2010 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).
We found 69 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.
In this systematic review we present information relating to the effectiveness and safety of the following interventions: anticonvulsants, antihypertensive drugs, antioxidants, antiplatelet drugs, atenolol, bed rest, hospital admission, or day care, calcium supplementation, choice of analgesia during labour, early delivery (interventionist care), evening primrose oil, fish oil, glyceryl trinitrate, magnesium supplementation, plasma volume expansion, and salt restriction.
Key Points
Pre-eclampsia (raised blood pressure and proteinuria) complicates 2% to 8% of pregnancies, and increases morbidity and mortality in the mother and child. Pre-eclampsia is more common in women with multiple pregnancy and in those with conditions associated with microvascular disease.
Antiplatelet drugs (primarily low-dose aspirin) reduce the risk of pre-eclampsia, death of the baby, and premature birth without increasing the risks of bleeding, in women at high risk of pre-eclampsia. Calcium supplementation reduces the risk of pre-eclampsia compared with placebo.We don't know whether fish oil, evening primrose oil, salt restriction, magnesium supplementation, or glyceryl trinitrate are beneficial in high-risk women because there are insufficient data to draw reliable conclusions. We don't know whether antioxidants reduce rates of pre-eclampsia as the data are inconsistent, although they are unlikely to reduce mortality.
We don't know whether atenolol reduces the risk of pre-eclampsia, but it may worsen outcomes for babies.
For women with mild to moderate hypertension during pregnancy, antihypertensive drugs reduce the risk of progression to severe hypertension, but may not improve other clinical outcomes. ACE inhibitors have been associated with fetal renal failure, and beta-blockers are associated with the baby being born small for its gestational age.We don't know whether bed rest or hospital admission are also beneficial.
There is consensus that women who develop severe hypertension in pregnancy should receive antihypertensive treatment, but we don't know which antihypertensive agent is most effective. We don't know whether plasma volume expansion, antioxidants, epidural analgesia, or early delivery improve outcomes for women with severe pre-eclampsia.
Magnesium sulphate reduces the risk of first or subsequent seizures in women with severe pre-eclampsia compared with placebo.
Magnesium sulphate reduces the risk of subsequent seizures in women with eclampsia compared with either phenytoin or diazepam, with fewer adverse effects for the mother or baby.
Related Articles
Cardiovascular mortality after pre-eclampsia in one child mothers: prospective, population based cohort study
Skjaerven, Rolv
Wilcox, Allen J
Klungsøyr, Kari
Irgens, Lorentz M
Vikse, Bjørn Egil
Vatten, Lars J
Lie, Rolv Terje
BMJ : British Medical Journal
Objective To assess the association of pre-eclampsia with later cardiovascular death in mothers according to their lifetime number of pregnancies, and particularly after only one child.
Design Prospective, population based cohort study.
Setting Medical Birth Registry of Norway.
Participants We followed 836 147 Norwegian women with a first singleton birth between 1967 and 2002 for cardiovascular mortality through linkage to the national Cause of Death Registry. About 23 000 women died by 2009, of whom 3891 died from cardiovascular causes. Associations between pre-eclampsia and cardiovascular death were assessed by hazard ratios, estimated by Cox regression analyses. Hazard ratios were adjusted for maternal education (three categories), maternal age at first birth, and year of first birth
Results The rate of cardiovascular mortality among women with preterm pre-eclampsia was 9.2% after having only one child, falling to 1.1% for those with two or more children. With term pre-eclampsia, the rates were 2.8% and 1.1%, respectively. Women with pre-eclampsia in their first pregnancy had higher rates of cardiovascular death than those who did not have the condition at first birth (adjusted hazard ratio 1.6 (95% confidence interval 1.4 to 2.0) after term pre-eclampsia; 3.7 (2.7 to 4.8) after preterm pre-eclampsia). Among women with only one lifetime pregnancy, the increase in risk of cardiovascular death was higher than for those with two or more children (3.4 (2.6 to 4.6) after term pre-eclampsia; 9.4 (6.5 to 13.7) after preterm pre-eclampsia). The risk of cardiovascular death was only moderately elevated among women with pre-eclamptic first pregnancies who went on to have additional children (1.5 (1.2 to 2.0) after term pre-eclampsia; 2.4 (1.5 to 3.9) after preterm pre-eclampsia). There was little evidence of additional risk after recurrent pre-eclampsia. All cause mortality for women with two or more lifetime births, who had pre-eclampsia in first pregnancy, was not elevated, even with preterm pre-eclampsia in first pregnancy (1.1 (0.87 to 1.14)).
Conclusions Cardiovascular death in women with pre-eclampsia in their first pregnancy is concentrated mainly in women with no additional births. This association might be due to health problems that discourage or prevent further pregnancies rather than to pre-eclampsia itself. As a screening criterion for cardiovascular disease risk, pre-eclampsia is a strong predictor primarily among women with only one child—particularly with preterm pre-eclampsia.
Related Articles
The APPLe Study: A Randomized, Community-Based, Placebo-Controlled Trial of Azithromycin for the Prevention of Preterm Birth, with Meta-Analysis
van den Broek, Nynke R.
White, Sarah A.
Goodall, Mark
Ntonya, Chikondi
Kayira, Edith
Kafulafula, George
Neilson, James P.
PLoS Medicine
In a randomized trial in Malawi of azithromycin versus placebo in over 2,000 pregnant women, Jim Neilson and colleagues show no benefit of azithromycin for a number of outcomes including preterm birth and prenatal death.
Premature birth is the major cause of perinatal mortality and morbidity in both high- and low-income countries. The causes of preterm labour are multiple but infection is important. We have previously described an unusually high incidence of preterm birth (20%) in an ultrasound-dated, rural, pregnant population in Southern Malawi with high burdens of infective morbidity. We have now studied the impact of routine prophylaxis with azithromycin as directly observed, single-dose therapy at two gestational windows to try to decrease the incidence of preterm birth.
Methods and Findings
We randomized 2,297 pregnant women attending three rural and one peri-urban health centres in Southern Malawi to a placebo-controlled trial of oral azithromycin (1 g) given at 16–24 and 28–32 wk gestation. Gestational age was determined by ultrasound before 24 wk. Women and their infants were followed up until 6 wk post delivery. The primary outcome was incidence of preterm delivery, defined as <37 wk. Secondary outcomes were mean gestational age at delivery, perinatal mortality, birthweight, maternal malaria, and anaemia. Analysis was by intention to treat. There were no significant differences in outcome between the azithromycin group (n = 1,096) and the placebo group (n = 1,087) in respect of preterm birth (16.8% versus 17.4%), odds ratio (OR) 0.96, 95% confidence interval (0.76–1.21); mean gestational age at delivery (38.5 versus 38.4 weeks), mean difference 0.16 (−0.08 to 0.40); mean birthweight (3.03 versus 2.99 kg), mean difference 0.04 (−0.005 to 0.08); perinatal deaths (4.3% versus 5.0%), OR 0.85 (0.53–1.38); or maternal malarial parasitaemia (11.5% versus 10.1%), OR 1.11 (0.84–1.49) and anaemia (44.1% versus 41.3%) at 28–32 weeks, OR 1.07 (0.88–1.30). Meta-analysis of the primary outcome results with seven other studies of routine antibiotic prophylaxis in pregnancy (>6,200 pregnancies) shows no effect on preterm birth (relative risk 1.02, 95% confidence interval 0.86–1.22).
This study provides no support for the use of antibiotics as routine prophylaxis to prevent preterm birth in high risk populations; prevention of preterm birth requires alternative strategies.
Trial registration
Current Controlled Trials ISRCTN84023116
Please see later in the article for the Editors' Summary
Editors' Summary
Most pregnancies last about 40 weeks. Labor that occurs before 37 weeks of gestation (the period during which a baby develops in its mother) is defined as a preterm birth. In industrialized countries, 5%–10% of all births are preterm. Figures for preterm births are harder to obtain for low-income countries because of uncertainties about gestational dates but, in both rich and poor countries, preterm birth is a major cause of infant death and illness around the time of birth. Babies who are born prematurely also often have long-term health problems and disabilities. There are many reasons why some babies are born prematurely. Structural problems such as a weak cervix (the neck of the womb, which dilates during labor to allow the baby to leave the mother's body) can result in a premature delivery, as can pregnancy-induced diabetes, blood-clotting disorders, bacterial infections in the vagina or the womb, and malaria. However, it is impossible to predict which mothers will spontaneously deliver early.
Why Was This Study Done?
At present there is no effective way to prevent premature births. Because infection is often associated with preterm labor and can occur early in pregnancy but remain undetected, one way to reduce the incidence of preterm births may be to give pregnant women antibiotics even when they have no obvious infection (prophylactic antibiotics). In this study, the researchers test this hypothesis by giving the antibiotic azithromycin to pregnant women living in Southern Malawi in a randomized, placebo-controlled trial. One baby in five is born before 37 weeks gestation in Southern Malawi and the women living in this part of sub-Saharan Africa have a high burden of infection. Azithromycin is a safe antibiotic that can treat many of the bacterial infections that have been implicated in preterm birth. It also has some antimalarial activity. In a randomized, placebo-controlled trial, participants are randomly assigned to receive a drug or identical-looking "dummy" tablets (placebo).
What Did the Researchers Do and Find?
The researchers enrolled more than 2,000 pregnant women into the APPLe study (Azithromycin for the Prevention of Preterm Labor) and determined the gestational age of their unborn babies using ultrasound. Half of the women were given an oral dose of azithromycin at 16–24 weeks and at 28–32 weeks gestation. The remaining women were given a placebo at similar times. The mothers and their babies were followed up until 6 weeks after delivery. There was no significant difference in the primary outcome of the study—the incidence of delivery before 37 weeks gestation—between the two groups of women. Secondary outcomes—including mean gestational age at delivery, mean birth weight, and still births and infant deaths within a week of birth—were also similar in the two groups of women. Finally, the researchers did a meta-analysis (a statistical technique that combines the results of several studies) of their study and seven published studies of routine antibiotic prophylaxis in pregnancy, which indicated that the prophylactic use of antibiotics did not alter the risk of preterm birth.
What Do These Findings Mean?
These findings provide no support for the use of antibiotics as prophylaxis to prevent preterm birth. The women included in this study had an unusually high incidence of preterm delivery and a high burden of infection so these findings may not be generalizable. The results of the meta-analysis, however, also provide no support for prophylactic antibiotics. Given that observational data have associated infection with preterm labor, why are the results of the APPLe trial and the meta-analysis negative? One possibility is that different antibiotics or dosing regimens might be more effective. Another possibility is that infection might be a secondary consequence of some other condition that causes preterm birth rather than the primary cause of early delivery. Whatever the reason for the lack of effect of prophylactic antibiotics, the researchers recommend that pregnant women should not be given antibiotics prophylactically to prevent preterm birth particularly since, in a recent study, the babies of women given antibiotics to halt ongoing preterm labor had an increased risk of developmental problems.
Additional Information
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1000191.
The March of Dimes, a nonprofit organization for pregnancy and baby health, provides information on preterm birth (in English and Spanish)
The Nemours Foundation, another nonprofit organization for child health, also provides information on premature babies (in English and Spanish)
Tommy's is a nonprofit organization that funds research and provides information on the causes and prevention of miscarriage, premature birth, and stillbirth
The US Centers for Disease Control and Prevention provides information on maternal and infant health (in English and Spanish)
The US National Women's Health Information Center has detailed information about pregnancy (in English and Spanish)
MedlinePlus provides links to other information on premature babies (in English and Spanish)
Related Articles
Prevention of congenital malformations and other adverse pregnancy outcomes with 4.0 mg of folic acid: community-based randomized clinical trial in Italy and the Netherlands
Bortolus, Renata
Blom, Fenneke
Filippini, Francesca
van Poppel, Mireille NM
Leoncini, Emanuele
de Smit, Denhard J
Benetollo, Pier Paolo
Cornel, Martina C
de Walle, Hermien EK
Mastroiacovo, Pierpaolo
BMC Pregnancy and Childbirth
In 2010 a Cochrane review confirmed that folic acid (FA) supplementation prevents the first- and second-time occurrence of neural tube defects (NTDs). At present some evidence from observational studies supports the hypothesis that FA supplementation can reduce the risk of all congenital malformations (CMs) or the risk of a specific and selected group of them, namely cardiac defects and oral clefts. Furthermore, the effects on the prevention of prematurity, foetal growth retardation and pre-eclampsia are unclear.
Although the most common recommendation is to take 0.4 mg/day, the problem of the most appropriate dose of FA is still open.
The aim of this project is to assess the effect a higher dose of peri-conceptional FA supplementation on reducing the occurrence of all CMs. Other aims include the promotion of pre-conceptional counselling, comparing rates of selected CMs, miscarriage, pre-eclampsia, preterm birth, small for gestational age, abruptio placentae.
This project is a joint effort by research groups in Italy and the Netherlands. Women of childbearing age, who intend to become pregnant within 12 months are eligible for the studies. Women are randomly assigned to receive 4 mg of FA (treatment in study) or 0.4 mg of FA (referent treatment) daily. Information on pregnancy outcomes are derived from women-and-physician information.
We foresee to analyze the data considering all the adverse outcomes of pregnancy taken together in a global end point (e.g.: CMs, miscarriage, pre-eclampsia, preterm birth, small for gestational age). A total of about 1,000 pregnancies need to be evaluated to detect an absolute reduction of the frequency of 8%. Since the sample size needed for studying outcomes separately is large, this project also promotes an international prospective meta-analysis.
The rationale of these randomized clinical trials (RCTs) is the hypothesis that a higher intake of FA is related to a higher risk reduction of NTDs, other CMs and other adverse pregnancy outcomes. Our hope is that these trials will act as catalysers, and lead to other large RCTs studying the effects of this supplementation on CMs and other infant and maternal outcomes.
Trial registration
Italian trial: ClinicalTrials.gov Identifier: NCT01244347.
Dutch trial: Dutch Trial Register ID: NTR3161.
Congenital malformations; Birth defects; Folic acid; Vitamins; Prevention; Prematurity; Birth weight; Pre-eclampsia; Meta-analysis
Related Articles
Population-based trends in pregnancy hypertension and pre-eclampsia: an international comparative study
Roberts, Christine L
Ford, Jane B
Algert, Charles S
Antonsen, Sussie
Chalmers, James
Cnattingius, Sven
Gokhale, Manjusha
Kotelchuck, Milton
Melve, Kari K
Langridge, Amanda
Morris, Carole
Morris, Jonathan M
Nassar, Natasha
Norman, Jane E
Norrie, John
Sørensen, Henrik Toft
Walker, Robin
Weir, Christopher J
BMJ Open
The objective of this study was to compare international trends in pre-eclampsia rates and in overall pregnancy hypertension rates (including gestational hypertension, pre-eclampsia and eclampsia).
Population data (from birth and/or hospital records) on all women giving birth were available from Australia (two states), Canada (Alberta), Denmark, Norway, Scotland, Sweden and the USA (Massachusetts) for a minimum of 6 years from 1997 to 2007. All countries used the 10th revision of the International Classification of Diseases, except Massachusetts which used the 9th revision. There were no major changes to the diagnostic criteria or methods of data collection in any country during the study period. Population characteristics as well as rates of pregnancy hypertension and pre-eclampsia were compared.
Absolute rates varied across the populations as follows: pregnancy hypertension (3.6% to 9.1%), pre-eclampsia (1.4% to 4.0%) and early-onset pre-eclampsia (0.3% to 0.7%). Pregnancy hypertension and/or pre-eclampsia rates declined over time in most populations. This was unexpected given that factors associated with pregnancy hypertension such as pre-pregnancy obesity and maternal age are generally increasing. However, there was also a downward shift in gestational age with fewer pregnancies reaching 40 weeks.
The rate of pregnancy hypertension and pre-eclampsia decreased in northern Europe and Australia from 1997 to 2007, but increased in Massachusetts. The use of a different International Classification of Diseases coding version in Massachusetts may contribute to the difference in trend. Elective delivery prior to the due date is the most likely explanation for the decrease observed in Europe and Australia. Also, the use of interventions that reduce the risk of pregnancy hypertension and/or progression to pre-eclampsia (low-dose aspirin, calcium supplementation and early delivery for mild hypertension) may have contributed to the decline.
Article summary
Article focus
The population prevalence of factors associated with increased and decreased risk of pregnancy hypertension and pre-eclampsia has changed over time, but the impact of these changes is unknown.
International comparisons of absolute population rates of pregnancy hypertension and pre-eclampsia are hindered by different diagnostic criteria and methods of data collection.
Comparing trends between countries overcomes the difficulties in comparing absolute rates.
Key message
Pregnancy hypertension and/or pre-eclampsia rates declined over time in northern Europe and Australia, but not Massachusetts (USA).
Declining hypertension rates were accompanied by a downward shift in gestational age with fewer pregnancies reaching term, the time when the pregnancy hypertension and pre-eclampsia are most likely to occur.
Strengths and limitations of this study
Strengths include numerous validation studies indicating that the hypertensive disorders are reliably reported in the population data sets used for the study and the consistency of trends across most countries.
Limitations include a different International Classification of Diseases coding version in Massachusetts and lack of available information on clinical interventions.
Trends; pregnancy; pre-eclampsia; gestational hypertension; international classification of diseases; maternal medicine; obstetrics; hypertension; epidemiology; statistics; epidmiology; delivery; birth; infant mortality; information; public health; health economics; health policy; international health services; quality in healthcare; health and socio-economic inequalities; maternal and child health; statistics and research methods; parturition; preterm birth
Related Articles
Intermittent oral iron supplementation during pregnancy (Review)
Peña-Rosas, Juan Pablo
De-Regil, Luz Maria
Dowswell, Therese
Viteri, Fernando E
The Cochrane database of systematic reviews
Anaemia is a frequent condition during pregnancy, particularly among women from developing countries who have insufficient iron intake to meet increased iron needs of both the mother and the fetus. Traditionally, gestational anaemia has been prevented with the provision of daily iron supplements throughout pregnancy, but adherence to this regimen due to side effects, interrupted supply of the supplements, and concerns about safety among women with an adequate iron intake, have limited the use of this intervention. Intermittent (i.e. one, two or three times a week on non-consecutive days) supplementation with iron alone or in combination with folic acid or other vitamins and minerals has recently been proposed as an alternative to daily supplementation.
To assess the benefits and harms of intermittent supplementation with iron alone or in combination with folic acid or other vitamins and minerals to pregnant women on neonatal and pregnancy outcomes.
Search methods
We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (23 March 2012). We also searched the WHO International Clinical Trials Registry Platform (ICTRP) for ongoing studies and contacted relevant organisations for the identification of ongoing and unpublished studies (23 March 2012).
Selection criteria
Randomised or quasi-randomised trials.
Data collection and analysis
We assessed the methodological quality of trials using standard Cochrane criteria. Two review authors independently assessed trial eligibility, extracted data and conducted checks for accuracy.
Main results
This review includes 21 trials from 13 different countries, but only 18 trials (with 4072 women) reported on our outcomes of interest and contributed data to the review. All of these studies compared daily versus intermittent iron supplementation.
Three studies provided iron alone, 12 iron+folic acid and three more iron plus multiple vitamins and minerals. Their methodological quality was mixed and most had high levels of attrition. Overall, there was no clear evidence of differences between groups for infant primary outcomes: low birthweight (average risk ratio (RR) 0.96; 95% confidence interval (CI) 0.61 to 1.52, seven studies), infant birthweight (mean difference MD −8.62 g; 95% CI −52.76 g to 35.52 g, eight studies), premature birth (average RR 1.82; 95% CI 0.75 to 4.40, four studies). None of the studies reported neonatal deaths or congenital anomalies.
For maternal outcomes, there was no clear evidence of differences between groups for anaemia at term (average RR 1.22; 95% CI 0.84 to 1.80, four studies) and women receiving intermittent supplementation had less side effects (average RR 0.56; 95% CI 0.37 to 0.84, 11 studies) than those receiving daily supplements. Women receiving intermittent supplements were also at lower risk of having high haemoglobin (Hb) concentrations (greater than 130 g/L) during the second or third trimester of pregnancy (average RR 0.48; 95% CI 0.35 to 0.67, 13 studies). There were no significant differences in iron-deficiency anaemia between women receiving intermittent or daily iron+folic acid supplementation (average RR 0.71; 95% CI 0.08 to 6.63, 1 study). There were no maternal deaths (six studies) or women with severe anaemia in pregnancy (six studies). None of the studies reported on iron deficiency at term or infections during pregnancy.
Where sufficient data were available for primary outcomes, we set up subgroups to look for possible differences between studies in terms of earlier or later supplementation; women's anaemia status at the start of supplementation; higher and lower weekly doses of iron; and the malarial status of the region in which the trials were conducted. There was no clear effect of these variables on the results of the review.
Authors' conclusions
The present systematic review is the most comprehensive summary of the evidence assessing the benefits and harms of intermittent iron supplementation regimens in pregnant women on haematological and pregnancy outcomes. The findings suggest that intermittent iron+folic acid regimens produce similar maternal and infant outcomes at birth as daily supplementation but are associated with fewer side effects. Women receiving daily supplements had increased risk of developing high levels of Hb in mid and late pregnancy but were less likely to present mild anaemia near term. Although the evidence is limited and the quality of the trials was low or very low, intermittent may be a feasible alternative to daily iron supplementation among those pregnant women who are not anaemic and have adequate antenatal care.
*Dietary Supplements [adverse effects]; Administration, Oral; Anemia, Iron-Deficiency [blood; *prevention & control]; Developing Countries; Drug Administration Schedule; Drug Combinations; Folic Acid [administration & dosage]; Hemoglobin A [metabolism]; Infant, Low Birth Weight; Infant, Newborn; Iron [*administration & dosage; adverse effects]; Iron, Dietary [*administration & dosage]; Pregnancy Complications, Hematologic [blood; prevention & control]; Premature Birth; Randomized Controlled Trials as Topic; Vitamins [administration & dosage]; Female; Humans; Pregnancy
Related Articles
Pre-eclampsia, soluble fms-like tyrosine kinase 1, and the risk of reduced thyroid function: nested case-control and population based study
Levine, Richard J
Vatten, Lars J
Horowitz, Gary L
Qian, Cong
Romundstad, Pal R
Yu, Kai F
Hollenberg, Anthony N
Hellevik, Alf I
Asvold, Bjorn O
Karumanchi, S Ananth
BMJ : British Medical Journal
Objective To determine if pre-eclampsia is associated with reduced thyroid function during and after pregnancy.
Design Nested case-control study during pregnancy and population based follow-up study after pregnancy.
Setting Calcium for Pre-eclampsia Prevention trial of healthy pregnant nulliparous women in the United States during 1992-5, and a Norwegian population based study (Nord-Trondelag Health Study or HUNT-2) during 1995-7 with linkage to the medical birth registry of Norway.
Participants All 141 women (cases) in the Calcium for Pre-eclampsia Prevention trial with serum measurements before 21 weeks' gestation (baseline) and after onset of pre-eclampsia (before delivery), 141 normotensive controls with serum measurements at similar gestational ages, and 7121 women in the Nord-Trondelag Health Study whose first birth had occurred in 1967 or later and in whom serum levels of thyroid stimulating hormone had been subsequently measured.
Main outcome measures Thyroid function tests and human chorionic gonadotrophin and soluble fms-like tyrosine kinase 1 concentrations in the Calcium for Pre-eclampsia Prevention cohort and odds ratios for levels of thyroid stimulating hormone above the reference range, according to pre-eclampsia status in singleton pregnancies before the Nord-Trondelag Health Study.
Results In predelivery specimens of the Calcium for Pre-eclampsia Prevention cohort after the onset of pre-eclampsia, thyroid stimulating hormone levels increased 2.42 times above baseline compared with a 1.48 times increase in controls. The ratio of the predelivery to baseline ratio of cases to that of the controls was 1.64 (95% confidence interval 1.29 to 2.08). Free triiodothyronine decreased more in the women with pre-eclampsia than in the controls (case ratio to control ratio 0.96, 95% confidence interval 0.92 to 0.99). The predelivery specimens but not baseline samples from women with pre-eclampsia were significantly more likely than those from controls to have concentrations of thyroid stimulating hormone above the reference range (adjusted odds ratio 2.2, 95% confidence interval 1.1 to 4.4). Both in women who developed pre-eclampsia and in normotensive controls the increase in thyroid stimulating hormone concentration between baseline and predelivery specimens was strongly associated with increasing quarters of predelivery soluble fms-like tyrosine kinase 1 (P for trend 0.002 and <0.001, respectively). In the Nord-Trondelag Health Study, women with a history of pre-eclampsia in their first pregnancy were more likely than other women (adjusted odds ratio 1.7, 95% confidence interval 1.1 to 2.5) to have concentrations of thyroid stimulating hormone above the reference range (>3.5 mIU/l). In particular, they were more likely to have high concentrations of thyroid stimulating hormone without thyroid peroxidase antibodies (adjusted odds ratio 2.6, 95% confidence interval 1.3 to 5.0), suggesting hypothyroid function in the absence of an autoimmune process. This association was especially strong (5.8, 1.3 to 25.5) if pre-eclampsia had occurred in both the first and the second pregnancies.
Conclusion Increased serum concentration of soluble fms-like tyrosine kinase 1 during pre-eclampsia is associated with subclinical hypothyroidism during pregnancy. Pre-eclampsia may also predispose to reduced thyroid function in later years.
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A Risk Prediction Model for the Assessment and Triage of Women with Hypertensive Disorders of Pregnancy in Low-Resourced Settings: The miniPIERS (Pre-eclampsia Integrated Estimate of RiSk) Multi-country Prospective Cohort Study
Payne, Beth A.
Hutcheon, Jennifer A.
Ansermino, J. Mark
Hall, David R.
Bhutta, Zulfiqar A.
Bhutta, Shereen Z.
Biryabarema, Christine
Grobman, William A.
Groen, Henk
Haniff, Farizah
Li, Jing
Magee, Laura A.
Merialdi, Mario
Nakimuli, Annettee
Qu, Ziguang
Sikandar, Rozina
Sass, Nelson
Sawchuck, Diane
Steyn, D. Wilhelm
Widmer, Mariana
Zhou, Jian
von Dadelszen, Peter
PLoS Medicine
Beth Payne and colleagues use a risk prediction model, the Pre-eclampsia Integrated Estimate of RiSk (miniPIERS) to help inform the clinical assessment and triage of women with hypertensive disorders of pregnancy in low-resourced settings.
Please see later in the article for the Editors' Summary
Pre-eclampsia/eclampsia are leading causes of maternal mortality and morbidity, particularly in low- and middle- income countries (LMICs). We developed the miniPIERS risk prediction model to provide a simple, evidence-based tool to identify pregnant women in LMICs at increased risk of death or major hypertensive-related complications.
Methods and Findings
From 1 July 2008 to 31 March 2012, in five LMICs, data were collected prospectively on 2,081 women with any hypertensive disorder of pregnancy admitted to a participating centre. Candidate predictors collected within 24 hours of admission were entered into a step-wise backward elimination logistic regression model to predict a composite adverse maternal outcome within 48 hours of admission. Model internal validation was accomplished by bootstrapping and external validation was completed using data from 1,300 women in the Pre-eclampsia Integrated Estimate of RiSk (fullPIERS) dataset. Predictive performance was assessed for calibration, discrimination, and stratification capacity. The final miniPIERS model included: parity (nulliparous versus multiparous); gestational age on admission; headache/visual disturbances; chest pain/dyspnoea; vaginal bleeding with abdominal pain; systolic blood pressure; and dipstick proteinuria. The miniPIERS model was well-calibrated and had an area under the receiver operating characteristic curve (AUC ROC) of 0.768 (95% CI 0.735–0.801) with an average optimism of 0.037. External validation AUC ROC was 0.713 (95% CI 0.658–0.768). A predicted probability ≥25% to define a positive test classified women with 85.5% accuracy. Limitations of this study include the composite outcome and the broad inclusion criteria of any hypertensive disorder of pregnancy. This broad approach was used to optimize model generalizability.
The miniPIERS model shows reasonable ability to identify women at increased risk of adverse maternal outcomes associated with the hypertensive disorders of pregnancy. It could be used in LMICs to identify women who would benefit most from interventions such as magnesium sulphate, antihypertensives, or transportation to a higher level of care.
Please see later in the article for the Editors' Summary
Editors' Summary
Each year, ten million women develop pre-eclampsia or a related hypertensive (high blood pressure) disorder of pregnancy and 76,000 women die as a result. Globally, hypertensive disorders of pregnancy cause around 12% of maternal deaths—deaths of women during or shortly after pregnancy. The mildest of these disorders is gestational hypertension, high blood pressure that develops after 20 weeks of pregnancy. Gestational hypertension does not usually harm the mother or her unborn child and resolves after delivery but up to a quarter of women with this condition develop pre-eclampsia, a combination of hypertension and protein in the urine (proteinuria). Women with mild pre-eclampsia may not have any symptoms—the condition is detected during antenatal checks—but more severe pre-eclampsia can cause headaches, blurred vision, and other symptoms, and can lead to eclampsia (fits), multiple organ failure, and death of the mother and/or her baby. The only "cure" for pre-eclampsia is to deliver the baby as soon as possible but women are sometimes given antihypertensive drugs to lower their blood pressure or magnesium sulfate to prevent seizures.
Why Was This Study Done?
Women in low- and middle-income countries (LMICs) are more likely to develop complications of pre-eclampsia than women in high-income countries and most of the deaths associated with hypertensive disorders of pregnancy occur in LMICs. The high burden of illness and death in LMICs is thought to be primarily due to delays in triage (the identification of women who are or may become severely ill and who need specialist care) and delays in transporting these women to facilities where they can receive appropriate care. Because there is a shortage of health care workers who are adequately trained in the triage of suspected cases of hypertensive disorders of pregnancy in many LMICs, one way to improve the situation might be to design a simple tool to identify women at increased risk of complications or death from hypertensive disorders of pregnancy. Here, the researchers develop miniPIERS (Pre-eclampsia Integrated Estimate of RiSk), a clinical risk prediction model for adverse outcomes among women with hypertensive disorders of pregnancy suitable for use in community and primary health care facilities in LMICs.
What Did the Researchers Do and Find?
The researchers used data on candidate predictors of outcome that are easy to collect and/or measure in all health care settings and that are associated with pre-eclampsia from women admitted with any hypertensive disorder of pregnancy to participating centers in five LMICs to build a model to predict death or a serious complication such as organ damage within 48 hours of admission. The miniPIERS model included parity (whether the woman had been pregnant before), gestational age (length of pregnancy), headache/visual disturbances, chest pain/shortness of breath, vaginal bleeding with abdominal pain, systolic blood pressure, and proteinuria detected using a dipstick. The model was well-calibrated (the predicted risk of adverse outcomes agreed with the observed risk of adverse outcomes among the study participants), it had a good discriminatory ability (it could separate women who had a an adverse outcome from those who did not), and it designated women as being at high risk (25% or greater probability of an adverse outcome) with an accuracy of 85.5%. Importantly, external validation using data collected in fullPIERS, a study that developed a more complex clinical prediction model based on data from women attending tertiary hospitals in high-income countries, confirmed the predictive performance of miniPIERS.
What Do These Findings Mean?
These findings indicate that the miniPIERS model performs reasonably well as a tool to identify women at increased risk of adverse maternal outcomes associated with hypertensive disorders of pregnancy. Because miniPIERS only includes simple-to-measure personal characteristics, symptoms, and signs, it could potentially be used in resource-constrained settings to identify the women who would benefit most from interventions such as transportation to a higher level of care. However, further external validation of miniPIERS is needed using data collected from women living in LMICs before the model can be used during routine antenatal care. Moreover, the value of miniPIERS needs to be confirmed in implementation projects that examine whether its potential translates into clinical improvements. For now, though, the model could provide the basis for an education program to increase the knowledge of women, families, and community health care workers in LMICs about the signs and symptoms of hypertensive disorders of pregnancy.
Additional Information
Please access these websites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001589.
The World Health Organization provides guidelines for the management of hypertensive disorders of pregnancy in low-resourced settings
The Maternal and Child Health Integrated Program provides information on pre-eclampsia and eclampsia targeted to low-resourced settings along with a tool-kit for LMIC providers
The US National Heart, Lung, and Blood Institute provides information about high blood pressure in pregnancy and a guide to lowering blood pressure in pregnancy
The UK National Health Service Choices website provides information about pre-eclampsia
The US not-for profit organization Preeclampsia Foundation provides information about all aspects of pre-eclampsia; its website includes some personal stories
The UK charity Healthtalkonline also provides personal stories about hypertensive disorders of pregnancy
MedlinePlus provides links to further information about high blood pressure and pregnancy (in English and Spanish); the MedlinePlus Encyclopedia has a video about pre-eclampsia (also in English and Spanish)
More information about miniPIERS and about fullPIERS is available
Related Articles
Pre-eclampsia, eclampsia, and hypertension
Duley, Lelia
BMJ Clinical Evidence
Pre-eclampsia (raised blood pressure and proteinuria) complicates 2-8% of pregnancies, and raises morbidity and mortality in the mother and child. Pre-eclampsia is more common in women with multiple pregnancy and in those who have conditions associates with microvascular disease.
Methods and outcomes
We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of preventive interventions in women at risk of pre-eclampsia? What are the effects of interventions in women who develop mild-moderate hypertension during pregnancy? What are the effects of interventions in women who develop severe pre-eclampsia or very high blood pressure during pregnancy? What is the best choice of anticonvulsant for women with eclampsia? We searched: Medline, Embase, The Cochrane Library, and other important databases up to June 2007 (BMJ Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).
We found 53 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.
In this systematic review we present information relating to the effectiveness and safety of the following interventions: anticonvulsants, antihypertensive drugs, antioxidants, antiplatelet drugs, atenolol, bed rest, hospital admission or day care, calcium supplementation, choice of analgesia during labour, early delivery (interventionist care), evening primrose oil, fish oil, glyceryl trinitrate, magnesium supplementation, plasma volume expansion, and salt restriction.
Key Points
Pre-eclampsia (raised blood pressure and proteinuria) complicates 2-8% of pregnancies, and increases morbidity and mortality in the mother and child. Pre-eclampsia is more common in women with multiple pregnancy, and in people with conditions associated with microvascular disease.
Antiplatelet drugs (primarily low-dose aspirin) reduce the risk of pre-eclampsia, death of the baby, and premature birth, without increasing the risks of bleeding, in women at high risk of pre-eclampsia. Calcium supplementation reduces the risk of pre-eclampsia compared with placebo.We don't know whether fish oil, evening primrose oil, salt restriction, magnesium supplementation, antioxidants, or glyceryl trinitrate are beneficial in high-risk women, because there are insufficient data to draw reliable conclusions.We don't know whether atenolol reduces the risk of pre-eclampsia, but it may worsen outcomes for babies.
For women with mild to moderate hypertension during pregnancy, antihypertensive drugs reduce the risk of progression to severe hypertension, but may not improve other clinical outcomes. ACE inhibitors have been associated with fetal renal failure, and beta-blockers are associated with the baby being born small for its gestational age.We don't know whether bed rest or hospital admission are also beneficial.
There is consensus that women who develop severe hypertension in pregnancy should receive antihypertensive treatment, but we don't know which antihypertensive agent is most effective. We don't know whether plasma volume expansion, antioxidants, epidural analgesia, or early delivery improve outcomes for women with severe pre-eclampsia.
Magnesium sulphate reduces the risk of first or subsequent seizures in women with severe pre-eclampsia compared with placebo.
Magnesium sulphate reduces the risk of subsequent seizures in women with eclampsia compared with either phenytoin or diazepam, with fewer adverse effects for the mother or baby.
Related Articles
Effects of alternative maternal micronutrient supplements on low birth weight in rural Nepal: double blind randomised community trial
Christian, Parul
Khatry, Subarna K
Katz, Joanne
Pradhan, Elizabeth K
LeClerq, Steven C
Shrestha, Sharada Ram
Adhikari, Ramesh K
Sommer, Alfred
West, Keith P
BMJ : British Medical Journal
To assess the impact on birth size and risk of low birth weight of alternative combinations of micronutrients given to pregnant women.
Double blind cluster randomised controlled trial.
Rural community in south eastern Nepal.
4926 pregnant women and 4130 live born infants.
426 communities were randomised to five regimens in which pregnant women received daily supplements of folic acid, folic acid-iron, folic acid-iron-zinc, or multiple micronutrients all given with vitamin A, or vitamin A alone (control).
Main outcome measures
Birth weight, length, and head and chest circumference assessed within 72 hours of birth. Low birth weight was defined <2500 g.
Supplementation with maternal folic acid alone had no effect on birth size. Folic acid-iron increased mean birth weight by 37 g (95% confidence interval −16 g to 90 g) and reduced the percentage of low birthweight babies (<2500 g) from 43% to 34% (16%; relative risk=0.84, 0.72 to 0.99). Folic acid-iron-zinc had no effect on birth size compared with controls. Multiple micronutrient supplementation increased birth weight by 64 g (12 g to 115 g) and reduced the percentage of low birthweight babies by 14% (0.86, 0.74 to 0.99). None of the supplement combinations reduced the incidence of preterm births. Folic acid-iron and multiple micronutrients increased head and chest circumference of babies, but not length.
Antenatal folic acid-iron supplements modestly reduce the risk of low birth weight. Multiple micronutrients confer no additional benefit over folic acid-iron in reducing this risk.
What is already known on this topicDeficiencies in micronutrients are common in women in developing countries and have been associated with low birth weight and preterm deliveryWhat this study addsIn rural Nepal maternal supplementation with folic acid-iron reduced the incidence of low birth weight by 16%A multiple micronutrient supplement of 14 micronutrients, including folic acid, iron, and zinc, reduced low birth weight by 14%, thus conferring no advantage over folic acid-iron
Related Articles
Essential pre-pregnancy and pregnancy interventions for improved maternal, newborn and child health
Lassi, Zohra S
Mansoor, Tarab
Salam, Rehana A
Das, Jai K
Bhutta, Zulfiqar A
Reproductive Health
2014;11(Suppl 1):S2.
The statistics related to pregnancy and its outcomes are staggering: annually, an estimated 250000-280000 women die during childbirth. Unfortunately, a large number of women receive little or no care during or before pregnancy. At a period of critical vulnerability, interventions can be effectively delivered to improve the health of women and their newborns and also to make their pregnancy safe. This paper reviews the interventions that are most effective during preconception and pregnancy period and synergistically improve maternal and neonatal outcomes. Among pre-pregnancy interventions, family planning and advocating pregnancies at appropriate intervals; prevention and management of sexually transmitted infections including HIV; and peri-conceptual folic-acid supplementation have shown significant impact on reducing maternal and neonatal morbidity and mortality. During pregnancy, interventions including antenatal care visit model; iron and folic acid supplementation; tetanus Immunisation; prevention and management of malaria; prevention and management of HIV and PMTCT; calcium for hypertension; anti-Platelet agents (low dose aspirin) for prevention of Pre-eclampsia; anti-hypertensives for treating severe hypertension; management of pregnancy-induced hypertension/eclampsia; external cephalic version for breech presentation at term (>36 weeks); management of preterm, premature rupture of membranes; management of unintended pregnancy; and home visits for women and children across the continuum of care have shown maximum impact on reducing the burden of maternal and newborn morbidity and mortality. All of the interventions summarized in this paper have the potential to improve maternal mortality rates and also contribute to better health care practices during preconception and periconception period.
preconception; prepregnancy; pregnancy; essential interventions
Related Articles
Daily oral iron supplementation during pregnancy
Peña-Rosas, Juan Pablo
De-Regil, Luz Maria
Dowswell, Therese
Viteri, Fernando E
The Cochrane database of systematic reviews
Iron and folic acid supplementation has been the preferred intervention to improve iron stores and prevent anaemia among pregnant women, and it may also improve other maternal and birth outcomes.
To assess the effects of daily oral iron supplements for pregnant women, either alone or in conjunction with folic acid, or with other vitamins and minerals as a public health intervention.
Search methods
We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (2 July 2012). We also searched the WHO International Clinical Trials Registry Platform (ICTRP) (2 July 2012) and contacted relevant organisations for the identification of ongoing and unpublished studies.
Selection criteria
Randomised or quasi-randomised trials evaluating the effects of oral preventive supplementation with daily iron, iron + folic acid or iron + other vitamins and minerals during pregnancy.
Data collection and analysis
We assessed the methodological quality of trials using standard Cochrane criteria. Two review authors independently assessed trial eligibility, extracted data and conducted checks for accuracy.
Main results
We included 60 trials. Forty-three trials, involving more than 27,402 women, contributed data and compared the effects of daily oral supplements containing iron versus no iron or placebo.
Overall, women taking iron supplements were less likely to have low birthweight newborns (below 2500 g) compared with controls (8.4% versus 10.2%, average risk ratio (RR) 0.81; 95% confidence interval (CI) 0.68 to 0.97, 11 trials, 8480 women) and mean birthweight was 30.81 g greater for those infants whose mothers received iron during pregnancy (average mean difference (MD) 30.81; 95% CI 5.94 to 55.68, 14 trials, 9385 women). Preventive iron supplementation reduced the risk of maternal anaemia at term by 70% (RR 0.30; 95% CI 0.19 to 0.46, 14 trials, 2199 women) and iron deficiency at term by 57% (RR 0.43; 95% CI 0.27 to 0.66, seven trials, 1256 women). Although the difference between groups did not reach statistical significance, women who received iron supplements were more likely than controls to report side effects (25.3% versus 9.91%) (RR 2.36; 95% CI 0.96 to 5.82, 11 trials, 4418 women), particularly at doses 60 mg of elemental iron or higher. Women receiving iron were on average more likely to have higher haemoglobin (Hb) concentrations at term and in the postpartum period, but were at increased risk of Hb concentrations greater than 130g/L during pregnancy and at term. Twenty-three studies were conducted in countries that in 2011 had some malaria risk in parts of the country. In some of these countries/territories, malaria is present only in certain areas or up to a particular altitude. Only two of these reported malaria outcomes. There is no evidence that iron supplementation increases placental malaria. For some outcomes heterogeneity was higher than 50%.
Authors' conclusions
Prenatal supplementation with daily iron are effective to reduce the risk of low birthweight, and to prevent maternal anaemia and iron deficiency in pregnancy. Associated maternal side effects and particularly high Hb concentrations during pregnancy at currently used doses suggest the need to update recommendations on doses and regimens for routine iron supplementation.
*Dietary Supplements [adverse effects]; Anemia, Iron-Deficiency [*prevention & control]; Folic Acid [*administration & dosage]; Infant, Low Birth Weight; Infant, Newborn; Iron [*administration & dosage]; Iron, Dietary [administration & dosage]; Pregnancy Complications, Hematologic [*prevention & control]; Pregnancy Outcome; Prenatal Care [methods]; Randomized Controlled Trials as Topic; Female; Humans; Pregnancy
Related Articles
Socio-demographic characteristics of women sustaining injuries during pregnancy: a study from the Danish National Birth Cohort
Virk, Jasveer
Hsu, Paul
Olsen, Jørn
BMJ Open
To describe adverse birth outcomes associated with hospital-treated injuries that took place among women in the Danish National Birth Cohort.
Longitudinal cohort study.
90 452 women and their offspring selected from the Danish National Birth Cohort.
Primary and secondary outcome measures
To determine if injured women were more likely to deliver an infant preterm, with low birth weight, stillborn or have a spontaneous abortion, the authors estimated HRs. ORs were generated to assess APGAR scores and infants born small for gestational age (SGA). Models were adjusted for maternal smoking and drinking during pregnancy, household socioeconomic status, eclampsia/pre-eclampsia or gestational diabetes status during pregnancy and maternal age at birth; estimates for preterm birth were also adjusted for prior history of preterm birth.
In the cohort of 90 452 pregnant women, 3561 (3.9%) received medical treatment for an injury during pregnancy. Injured pregnant women were more likely to deliver infants that were stillborn or have pregnancies terminated by spontaneous abortion. The authors did not detect an adverse effect between injuries sustained during pregnancy and delivery of preterm, low birth weight or SGA infants, or infants with an APGAR score of <7.
The study shows that injuries occurring among women from an unselected population may not have an adverse effect on birth weight, gestational age, APGAR score or SGA status but may adversely affect the risk of stillbirth and spontaneous abortions in some situations.
Article summary
Article focus
We describe adverse birth outcomes associated with injuries that took place among pregnant women in the Danish National Birth Cohort and include in our assessment injury severity, cause and mechanism.
Key messages
Injured pregnant women were more likely to deliver infants that were stillborn or have pregnancies that were terminated by spontaneous abortion. We did not detect an adverse effect between injuries sustained during pregnancy and delivery of preterm, low birth weight or SGA infants, or infants with an APGAR score of <7.
Women sustaining head or neck injuries were more likely to deliver an infant SGA and have a stillbirth, though these results were not statistically significant.
Strengths and limitations of this study
Previous studies have selected pregnant trauma patients or emergency room patients; our study, however, presents injuries among pregnant women from a general population.
We only have data on late spontaneous abortions, and if injured fetuses are aborted early, we would not detect an association.
Related Articles
Vitamin D supplementation for women during pregnancy
De-Regil, Luz Maria
Palacios, Cristina
Ansary, Ali
Kulier, Regina
Peña-Rosas, Juan Pablo
The Cochrane database of systematic reviews
Vitamin D deficiency or insufficiency is thought to be common among pregnant women. Vitamin D supplementation during pregnancy has been suggested as an intervention to protect against adverse gestational outcomes.
To examine whether supplements with vitamin D alone or in combination with calcium or other vitamins and minerals given to women during pregnancy can safely improve maternal and neonatal outcomes.
Search methods
We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 October 2011), the International Clinical Trials Registry Platform (ICTRP) (31 October 2011), the Networked Digital Library of Theses and Dissertations (28 October 2011) and also contacted relevant organisations (8 April 2011).
Selection criteria
Randomised and quasi-randomised trials with randomisation at either individual or cluster level, evaluating the effect of supplementation with vitamin D alone or in combination with other micronutrients for women during pregnancy.
Data collection and analysis
Two review authors independently i) assessed the eligibility of studies against the inclusion criteria ii) extracted data from included studies, and iii) assessed the risk of bias of the included studies. Data were checked for accuracy.
Main results
The search strategy identified 34 potentially eligible references. We included six trials assessing a total of 1023 women, excluded eight studies, and 10 studies are still ongoing. Five trials involving 623 women compared the effects of vitamin D alone versus no supplementation/placebo and one trial with 400 women compared the effects of vitamin D and calcium versus no supplementation.
Only one trial with 400 women reported on pre-eclampsia: women who received 1200 IU vitamin D along with 375 mg of elemental calcium per day were as likely to develop pre-eclampsia as women who received no supplementation (average risk ratio (RR) 0.67; 95% confidence interval (CI) 0.33 to 1.35). Data from four trials involving 414 women consistently show that women who received vitamin D supplements had higher concentrations of vitamin D in serum at term than those women who received no intervention or a placebo; however the magnitude of the response was highly heterogenous.
Data from three trials involving 463 women suggest that women who receive vitamin D supplements during pregnancy less frequently had a baby with a birthweight below 2500 grams than those women receiving no treatment or placebo; statistical significance was borderline (RR 0.48; 95% CI 0.23 to 1.01).
In terms of other conditions, there were no significant differences in adverse side effects including nephritic syndrome (RR 0.17; 95% CI 0.01 to 4.06; one trial, 135 women); stillbirths (RR 0.17; 95% CI 0.01 to 4.06; one trial, 135 women) or neonatal deaths (RR 0.17; 95% CI 0.01 to 4.06; one trial, 135 women) between women who received vitamin D supplements in comparison with women who received no treatment or placebo. No studies reported on preterm birth, maternal death, admission to neonatal intensive care unit/special nursery or Apgar scores.
Authors' conclusions
Vitamin D supplementation in a single or continued dose during pregnancy increases serum vitamin D concentrations as measured by 25-hydroxyvitamin D at term. The clinical significance of this finding and the potential use of this intervention as a part of routine antenatal care are yet to be determined as the number of high quality trials and outcomes reported is too limited to draw conclusions on its usefulness and safety. Further rigorous randomised trials are required to evaluate the role of vitamin D supplementation in pregnancy.
Related Articles
Long term mortality of mothers and fathers after pre-eclampsia: population based cohort study
Irgens, Henrik U
Reisæter, Lars
Irgens, Lorentz M
Lie, Rolv T
BMJ : British Medical Journal
To assess whether mothers and fathers have a higher long term risk of death, particularly from cardiovascular disease and cancer, after the mother has had pre-eclampsia.
Population based cohort study of registry data.
Mothers and fathers of all 626 272 births that were the mothers' first deliveries, recorded in the Norwegian medical birth registry from 1967 to 1992. Parents were divided into two cohorts based on whether the mother had pre-eclampsia during the pregnancy. Subjects were also stratified by whether the birth was term or preterm, given that pre-eclampsia might be more severe in preterm pregnancies.
Main outcome measures
Total mortality and mortality from cardiovascular causes, cancer, and stroke from 1967 to 1992, from data from the Norwegian registry of causes of death.
Women who had pre-eclampsia had a 1.2-fold higher long term risk of death (95% confidence interval 1.02 to 1.37) than women who did not have pre-eclampsia. The risk in women with pre-eclampsia and a preterm delivery was 2.71-fold higher (1.99 to 3.68) than in women who did not have pre-eclampsia and whose pregnancies went to term. In particular, the risk of death from cardiovascular causes among women with pre-eclampsia and a preterm delivery was 8.12-fold higher (4.31 to 15.33). However, these women had a 0.36-fold (not significant) decreased risk of cancer. The long term risk of death was no higher among the fathers of the pre-eclamptic pregnancies than the fathers of pregnancies in which pre-eclampsia did not occur.
Genetic factors that increase the risk of cardiovascular disease may also be linked to pre-eclampsia. A possible genetic contribution from fathers to the risk of pre-eclampsia was not reflected in increased risks of death from cardiovascular causes or cancer among fathers.
What is already known on this topicMaternal and fetal genes (including those inherited from the father) may contribute to pre-eclampsia, which occurs in 3-5% of pregnanciesOne set of candidate genes for pre-eclampsia is the maternal genes for thrombophilia, which may increase the mother's risk of death from cardiovascular diseaseWhat this study addsWomen who have pre-eclampsia during a pregnancy that ends in a preterm delivery have an eightfold higher risk of death from cardiovascular disease compared with women who do not have pre-eclampsia and whose pregnancy goes to termFathers of pregnancies in which pre-eclampsia occurred have no increased risk of death from cardiovascular diseaseThese results are compatible with maternal genes for thrombophilia having an effect on the risk of pre-eclampsia and of death from cardiovascular disease
Related Articles
Impact of micronutrient supplementation during pregnancy on birth weight, duration of gestation, and perinatal mortality in rural western China: double blind cluster randomised controlled trial
Zeng, Lingxia
Cheng, Yue
Dang, Shaonong
Yan, Hong
Dibley, Michael J
Chang, Suying
Kong, Lingzhi
BMJ : British Medical Journal
Objective To examine the impact of antenatal supplementation with multiple micronutrients or iron and folic acid compared with folic acid alone on birth weight, duration of gestation, and maternal haemoglobin concentration in the third trimester.
Design Cluster randomised double blind controlled trial.
Setting Two rural counties in north west China.
Participants 5828 pregnant women and 4697 live births.
Interventions Villages were randomised for all pregnant women to take either daily folic acid (control), iron with folic acid, or multiple micronutrients with a recommended allowance of 15 vitamins and minerals.
Main outcome measures Birth weight, length, and head circumference measured within 72 hours after delivery. Neonatal survival assessed at the six week follow-up visit.
Results Birth weight was 42 g (95% confidence interval 7 to 78 g) higher in the multiple micronutrients group compared with the folic acid group. Duration of gestation was 0.23 weeks (0.10 to 0.36 weeks) longer in the iron-folic acid group and 0.19 weeks (0.06 to 0.32 weeks) longer in the multiple micronutrients group. Iron-folic acid was associated with a significantly reduced risk of early preterm delivery (<34 weeks) (relative risk 0.50, 0.27 to 0.94, P=0.031). There was a significant increase in haemoglobin concentration in both iron-folic acid (5.0 g/l, 2.0 to 8.0 g/l, P=0.001) and multiple micronutrients (6.9 g/l, 4.1 to 9.6 g/l, P<0.001) groups compared with folic acid alone. In post hoc analyses there were no significant differences for perinatal mortality, but iron-folic acid was associated with a significantly reduced early neonatal mortality by 54% (relative risk 0.46, 0.21 to 0.98).
Conclusion In rural populations in China antenatal supplementation with iron-folic acid was associated with longer gestation and a reduction in early neonatal mortality compared with folic acid. Multiple micronutrients were associated with modestly increased birth weight compared with folic acid, but, despite this weight gain, there was no significant reduction in early neonatal mortality. Pregnant women in developing countries need sufficient doses of iron in nutrient supplements to maximise reductions in neonatal mortality.
Trial registration ISRCTN08850194.
Related Articles
Folic acid supplementation, dietary folate intake during pregnancy and risk for spontaneous preterm delivery: a prospective observational cohort study
Sengpiel, Verena
Bacelis, Jonas
Myhre, Ronny
Myking, Solveig
Pay, Aase Devold
Haugen, Margaretha
Brantsæter, Anne-Lise
Meltzer, Helle Margrete
Nilsen, Roy M
Magnus, Per
Vollset, Stein Emil
Nilsson, Staffan
Jacobsson, Bo
BMC Pregnancy and Childbirth
Health authorities in numerous countries recommend periconceptional folic acid to pregnant women to prevent neural tube defects. The objective of this study was to examine the association of folic acid supplementation during different periods of pregnancy and of dietary folate intake with the risk of spontaneous preterm delivery (PTD).
The Norwegian Mother and Child Cohort Study is a population-based prospective cohort study. A total of 65,668 women with singleton pregnancies resulting in live births in 1999–2009 were included. Folic acid supplementation was self-reported from 26 weeks before pregnancy until week 24 during pregnancy. At gestational week 22, the women completed a food frequency questionnaire, which allowed the calculation of their average total folate intake from foods and supplements for the first 4–5 months of pregnancy. Spontaneous PTD was defined as the spontaneous onset of delivery between weeks 22+0 and 36+6 (n = 1,628).
The median total folate intake was 266 μg/d (interquartile range IQR 154–543) in the overall population and 540 μg/d (IQR 369–651) in the supplement users. Eighty-three percent reported any folic acid supplementation from <8 weeks before to 24 weeks after conception while 42% initiated folic acid supplementation before their pregnancy. Cox regression analysis showed that the amount of folate intake from the diet (hazard ratio HR 1.16; confidence interval CI 0.65-2.08) and from the folic acid supplements (HR 1.04; CI 0.95-1.13) was not significantly associated with the risk of PTD. The initiation of folic acid supplementation more than 8 weeks before conception was associated with an increased risk for PTD (HR 1.19; CI 1.05-1.34) compared to no folic acid supplementation pre-conception. There was no significant association with PTD when supplementation was initiated within 8 weeks pre-conception (HR 1.01; CI 0.88-1.16). All analyses were adjusted for maternal characteristics and socioeconomic, health and dietary variables.
Our findings do not support a protective effect of dietary folate intake or folic acid supplementation on spontaneous PTD. Pre-conceptional folic acid supplementation starting more than 8 weeks before conception was associated with an increased risk of PTD. These results require further investigation before discussing an expansion of folic acid supplementation guidelines.
Pregnancy; Preterm delivery; Preterm birth; Gestational length; Folate; Folic acid supplementation
Related Articles
Clinical risk prediction for pre-eclampsia in nulliparous women: development of model in international prospective cohort
North, Robyn A
McCowan, Lesley M E
Dekker, Gustaaf A
Poston, Lucilla
Chan, Eliza H Y
Stewart, Alistair W
Black, Michael A
Taylor, Rennae S
Walker, James J
Baker, Philip N
Kenny, Louise C
BMJ : British Medical Journal
Objectives To develop a predictive model for pre-eclampsia based on clinical risk factors for nulliparous women and to identify a subgroup at increased risk, in whom specialist referral might be indicated.
Design Prospective multicentre cohort.
Setting Five centres in Auckland, New Zealand; Adelaide, Australia; Manchester and London, United Kingdom; and Cork, Republic of Ireland.
Participants 3572 "healthy" nulliparous women with a singleton pregnancy from a large international study; data on pregnancy outcome were available for 3529 (99%).
Main outcome measure Pre-eclampsia defined as ≥140 mm Hg or diastolic blood pressure ≥90 mm Hg, or both, on at least two occasions four hours apart after 20 weeks' gestation but before the onset of labour, or postpartum, with either proteinuria or any multisystem complication. Preterm pre-eclampsia was defined as women with pre-eclampsia delivered before 37+0 weeks' gestation. In the stepwise logistic regression the comparison group was women without pre-eclampsia.
Results Of the 3529 women, 186 (5.3%) developed pre-eclampsia, including 47 (1.3%) with preterm pre-eclampsia. Clinical risk factors at 14-16 weeks' gestation were age, mean arterial blood pressure, body mass index (BMI), family history of pre-eclampsia, family history of coronary heart disease, maternal birth weight, and vaginal bleeding for at least five days. Factors associated with reduced risk were a previous single miscarriage with the same partner, taking at least 12 months to conceive, high intake of fruit, cigarette smoking, and alcohol use in the first trimester. The area under the receiver operating characteristics curve (AUC), under internal validation, was 0.71. Addition of uterine artery Doppler indices did not improve performance (internal validation AUC 0.71). A framework for specialist referral was developed based on a probability of pre-eclampsia generated by the model of at least 15% or an abnormal uterine artery Doppler waveform in a subset of women with single risk factors. Nine per cent of nulliparous women would be referred for a specialist opinion, of whom 21% would develop pre-eclampsia. The relative risk for developing pre-eclampsia and preterm pre-eclampsia in women referred to a specialist compared with standard care was 5.5 and 12.2, respectively.
Conclusions The ability to predict pre-eclampsia in healthy nulliparous women using clinical phenotype is modest and requires external validation in other populations. If validated, it could provide a personalised clinical risk profile for nulliparous women to which biomarkers could be added.
Trial registration ACTRN12607000551493.
Related Articles
Multiple micronutrient supplementation during pregnancy in low-income countries: A meta-analysis of effects on birth size and length of gestation
Fall, Caroline H. D.
Fisher, David J.
Osmond, Clive
Margetts, Barrie M.
Food and nutrition bulletin
2009;30(4 Suppl):S533-S546.
Multiple micronutrient deficiencies are common among women in low-income countries and may adversely affect pregnancy outcomes.
This meta-analysis reports the effects on newborn size and duration of gestation of multiple micronutrient supplementation mainly compared with iron plus folic acid during pregnancy in recent randomized, controlled trials.
Original data from 12 randomized, controlled trials in Bangladesh, Burkina Faso, China, Guinea-Bissau, Indonesia, Mexico, Nepal, Niger, Pakistan, and Zimbabwe, all providing approximately 1 recommended dietary allowance (RDA) of multiple micronutrients to presumed HIV-negative women, were included. Outcomes included birthweight, other birth measurements, gestation, and incidence of low birthweight (LBW) (< 2,500 g), small-for-gestational age birth (SGA, birthweight below the within-each-population 10th percentile), large-for-gestational age birth (LGA, birthweight above the within-each-population 90th percentile), and preterm delivery (< 37 weeks).
Compared with control supplementation (mainly with iron–folic acid), multiple micronutrient supplementation was associated with an increase in mean birthweight (pooled estimate: +22.4 g [95% CI, 8.3 to 36.4 g]; p = .002), a reduction in the prevalence of LBW (pooled OR = 0.89 [95% CI, 0.81 to 0.97]; p = .01) and SGA birth (pooled OR = 0.90 [95% CI, 0.82 to 0.99]; p = .03), and an increase in the prevalence of LGA birth (pooled OR = 1.13 [95% CI, 1.00 to 1.28]; p = .04). In most studies, the effects on birthweight were greater in mothers with higher body mass index (BMI). In the pooled analysis, the positive effect of multiple micronutrients on birthweight increased by 7.6 g (95% CI, 1.9 to 13.3 g) per unit increase in maternal BMI (p for interaction = .009). The intervention effect relative to the control group was + 39.0 g (95% CI, +22.0 to +56.1 g) in mothers with BMI of 20 kg/m2 or higher compared with –6.0 g (95% CI, –8.8 to +16.8 g) in mothers with BMI under 20 kg/m2. There were no significant effects of multiple micronutrient supplementation on birth length or head circumference nor on the duration of gestation (pooled effect: +0.17 day [95% CI, –0.35 to +0.70 day]; p = .51) or the incidence of preterm birth (pooled OR = 1.00 [95% CI, 0.93 to 1.09]; p = .92).
Compared with iron–folic acid supplementation alone, maternal supplementation with multiple micronutrients during pregnancy in low-income countries resulted in a small increase in birthweight and a reduction in the prevalence of LBW of about 10%. The effect was greater among women with higher BMI.
Birth outcomes; birthweight; iron–folic acid; maternal body mass index; meta-analysis; multiple micronutrients; pregnancy; preterm delivery
Related Articles
Can changes in angiogenic biomarkers between the first and second trimesters of pregnancy predict development of pre-eclampsia in a low-risk nulliparous patient population?
Myatt, L
Clifton, RG
Roberts, JM
Spong, CY
Wapner, RJ
Thorp, JM
Mercer, BM
Peaceman, AM
Ramin, SM
Carpenter, MW
Sciscione, A
Tolosa, JE
Saade, G
Sorokin, Y
Anderson, GD
BJOG : an international journal of obstetrics and gynaecology
To determine if change in maternal angiogenic biomarkers between the first and second trimesters predicts pre-eclampsia in low-risk nulliparous women.
A nested case–control study of change in maternal plasma soluble Flt-1 (sFlt-1), soluble endoglin (sEng) and placenta growth factor (PlGF). We studied 158 pregnancies complicated by pre-eclampsia and 468 normotensive nonproteinuric controls.
A multicentre study in 16 academic medical centres in the USA.
Low-risk nulliparous women.
Luminex assays for PlGF, sFlt-1 and sEng performed on maternal EDTA plasma collected at 9–12, 15–18 and 23–26 weeks of gestation. Rate of change of analyte between first and either early or late second trimester was calculated with and without adjustment for baseline clinical characteristics.
Main outcome measures
Change in PlGF, sFlt-1 and sEng.
Rates of change of PlGF, sEng and sFlt-1 between first and either early or late second trimesters were significantly different in women who developed pre-eclampsia, severe pre-eclampsia or early-onset pre-eclampsia compared with women who remained normotensive. Inclusion of clinical characteristics (race, body mass index and blood pressure at entry) increased sensitivity for detecting severe and particularly early-onset pre-eclampsia but not pre-eclampsia overall. Receiver operating characteristics curves for change from first to early second trimester in sEng, PlGF and sFlt-1 with clinical characteristics had areas under the curve of 0.88, 0.84 and 0.86, respectively, and for early-onset pre-eclampsia with sensitivities of 88% (95% CI 64–99%), 77% (95% CI 50–93%) and 77% (95%CI 50–93%) for 80% specificity, respectively. Similar results were seen in the change from first to late second trimester.
Change in angiogenic biomarkers between first and early second trimester combined with clinical characteristics has strong utility for predicting early-onset pre-eclampsia.
Angiogenesis; endoglin; platelet growth factor; pre-eclampsia; sFlt-1
Related Articles
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