gynecology and obstetrics
Preterm Labor
Treatment
Antibiotics for group B streptococci, pending anovaginal culture results Tocolytics Sometimes corticosteroids (eg, between 24 and 34 weeks) Consideration of progestin in future pregnancies Bed rest and hydration are commonly used initially. Management of preterm labor may also include antibiotics, tocolytics, and corticosteroids ( Treatment references ). Antibiotics effective against group B streptococci are given pending negative anovaginal cultures ( Treatment references ). Choices for antibiotics include the following: For women without penicillin allergy:Penicillin G5 million units IV followed by 2.5 million units every 4 hours orampicillin2 g IV followed by 1 g every 4 hours For women with penicillin allergy but a low risk of anaphylaxis (eg, maculopapular rash with prior use):Cefazolin2 g IV followed by 1 g every 8 hours For women with penicillin allergy and an increased risk of anaphylaxis (eg, bronchospasm, angioneurotic edema, or hypotension with prior use, particularly within 30 minutes of exposure):Clindamycin900 mg IV every 8 hours if anovaginal cultures show susceptibility; if cultures document resistance or results are unavailable,vancomycin20 mg/kg IV every 8 hours (maximum dose of 2 g) If the cervix dilates, tocolytics (drugs that stop uterine contractions) can usually delay labor for at least 48 hours so that corticosteroids can be given to reduce risks to the fetus. Tocolytics include Magnesium sulfate A calcium channel blocker Prostaglandin inhibitors No tocolytic is clearly the first-line choice; choice should be individualized to minimize adverse effects. Magnesium sulfate is commonly used and is typically well-tolerated. IV magnesium sulfate should be considered in pregnancies < 32 weeks. In utero exposure to the drug appears to reduce the risk of severe neurologic dysfunction (eg, due to intraventricular hemorrhage), including cerebral palsy, in neonates. Prostaglandin inhibitors may cause transient oligohydramnios. They are contraindicated after 32 weeks gestation because they may cause premature narrowing or closure of the ductus arteriosus. If the fetus is ≥ 24 weeks and<34 weeks, women are given corticosteroids unless delivery is imminent. Another course of corticosteroids can be considered if all of the following are present: The pregnancy is < 34 weeks. Women are at risk of delivering within 7 days. The last course was given ≥ 14 days prior ( Treatment references , Corticosteroids should also be considered in the following circumstances At gestational age 34 weeks 0 days to 36 weeks 6 days if women are at risk of delivering within 7 days and no prior corticosteroids have been given ( Treatment references , Starting at gestational age 23 weeks 0 days if there is a risk of preterm delivery within 7 days ( Treatment references , One of the following corticosteroids may be used: Betamethasone12 mg IM every 24 hours for 2 doses Dexamethasone6 mg IM every 12 hours for 4 doses These corticosteroids accelerate maturation of fetal lungs and decrease risk of neonatal respiratory distress syndrome, intracranial bleeding, and mortality. A progestin has been recommended in future pregnancies for women who have a preterm delivery to reduce the risk of recurrence. This treatment is initiated during the 2nd trimester and continued until just before delivery. caproate (17-OHPC; Treatment references ). But in a recent international study of women who had had a preterm birth, 17-OHPC was no more effective than placebo ( 1.American College of Obstetricians and Gynecologists’ Committee on Practice Bulletins—Obstetrics: Practice Bulletin No. 171: Management of Preterm Labor.Obstet Gynecol128(4):e155-64. doi: 10.1097/AOG.0000000000001711 2.American College of Obstetricians and Gynecologists (ACOG): Prevention of group B streptococcal early-onset disease in newborns: ACOG Committee Opinion, Number 797.Obstet Gynecol135 (2):e51–e72, 2020. 3.American College of Obstetricians and Gynecologists: Committee Opinion No. 713 Summary: Antenatal corticosteroid therapy for fetal maturation.Obstet Gynecol130(2):493–494, 2017. doi: 10.1097/AOG.0000000000002231 4.Meis PJ, Klebanoff M, Thom E, et al: Prevention of recurrent preterm delivery by 17 alpha-hydroxyprogesteronecaproate.N Engl J Med348(24):2379–2385, 2003. 5.Blackwell SC, Gyamfi-Bannerman C, Biggio JR Jr, et al: 17-OHPC to prevent recurrent preterm birth in singleton gestations (PROLONG Study): A multicenter, international, randomized double-blind trial.Am J PerinatolOct 25, 2019. doi: 10.1055/s-0039-3400227 [Epub ahead of print] 6.Society for Maternal-Fetal Medicine (SMFM) Publications Committee: SMFM Statement: Use of 17-alphahydroxyprogesteronecaproate for prevention of recurrent preterm birth. Accessed 4/23/21. 7.American College of Obstetricians and Gynecologists (ACOG): ACOG statement on FDA proposal to withdraw 17phydroxyprogesteronecaproate. 2020. Accessed 7/3/21. 