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A study on bacterial vaginosis in pregnancy and its effect on pregnancy outcome

Current studies have found that the prevalence of BV ranges from 15% to 30% among non-pregnant women and 10% to 41% among pregnant women. It is a complex alteration of the vaginal ecosystem, characterized by a shift in the vaginal flora from the normally predominant Lacto bacilli to overgrowth of mixed flora, including Gardenella Vaginalis, Mobiluncus, Provotella, Bacteroides and Mycoplasma species. BV results in an elevated pH, increased vaginal fluid concentration of diamines, polyamines, organic acids, as well as enzymes such as mucinase, sialidase, IgA, proteases, collagenase, phospholipase A2 and C, endotoxin, cytokine, interleukin 1-α and prostaglandins E2 and F2α. It is likely that these enzymes and organic compounds serve to overcome host defence mechanisms, facilitate the entrance of cervicovaginal microorganisms into the upper reproductive tract and contribute to the ABSTRACT

initiation of associated complications like preterm labour, spontaneous abortion, premature rupture of membranes, preterm premature rupture of membranes, chorioamnionitis, postpartum endometritis, post caesarean wound infection and neonatal complications. 4 The recent awareness of the possible adverse sequelae of BV during pregnancy has led to more attention to screening and treating women during pregnancy. Also, the availability of more rapid, easier and less expensive tests have made it easier to screen the pregnant women.
The aims and objectives of this study are to study the incidence and risk factors of BV in pregnancy and to assess the feto-maternal outcome at Narayana Medical College and Hospital, Nellore for a period of 2 years.

METHODS
This prospective study was conducted among 150 pregnant women who attended the antenatal outpatient and inpatient clinic of the Department of Obstetrics and Gynaecology at Narayana Medical College Hospital, Nellore over a period of two years (October 2016 to October 2018).
Obstetric cases fulfilling the inclusion and exclusion criteria were enrolled in the study by convenient sampling technique. They were followed till the outcome of pregnancy. The data was subjected to usual statistical analysis by employing the chi-square tests.

Inclusion criteria
• All pregnant women who visited the antenatal clinic at Narayana Medical College and Hospital with or without symptoms, irrespective of age, parity and period of gestation will be screened for BV after due informed consent.

Clue cells by wet mount preparation
Presence of vaginal epithelial cells with borders obscured with small adherent bacteria called "clue cells". Microscopic examination of a saline wet mount preparation of vaginal discharge is done. A drop of discharge was mixed with a drop of normal saline on a glass slide, covered with a clean cover slip and examined under a high power for the presence of epithelial cells, clue cells, pus cells Trichomonas vaginalis and Candida.

Incidence of BV
During the study period (2 years), among 150 pregnant women, 30 were diagnosed to have BV and the incidence is 20%. (Figure1).

Figure 1: Incidence of BV among study population.
In the present study, age distribution varied from 18 -36 years. BV is found significantly more among the younger age group (18 to 20 yrs). There is no actual correlation between age and BV (Table 1).

Relation between parity and BV
In the present study, 73.3 % were primigravida with a pvalue 0.016 which is significant. In BV +ve women, 16.7% were Gravida 2, and 10% were multigravida. But parity has no direct relationship with BV ( Table 2).

Distribution of study population based on SES
In the present study, 63.4 % of BV +ve women belong to low SES (Class IV and V) based on modified Kuppuswamy scale, as most of the study population belong to rural areas (Table 3).

Mean gestational age for swab test
A vaginal swab was taken to all antenatal women irrespective of gestational age to screen BV. The mean gestational age at which swab was taken did not differ significantly between BV + ve andve women (Table  4).

Incidence of preterm labour among study population
In the present study, 30% of BV +ve women had preterm labour and 8.3% of BV -ve women had preterm labor. 70% of BV +ve and 91.7% of BV-ve had term delivery. Preterm labor is significantly (p<0.001) more common with BV (Table 5). PPROM is statistically significant in BV +ve women with a p value of 0.004 (Table 6).

Incidence of PROM in study population
In the present study, only 10% with BV had PROM, with a p-value 0.20, which is not significant. 7.5% of BV -ve women had PROM (Table 7).

Incidence of low birth weight among study population
Birth weight is significantly less among patients with BV. The mean B.wt in BV+ve is 2.45. The lower birth weight associated with BV could have been because of lower gestational age at birth in BV positive patients. Therefore an ANCOVA test was performed to see whether b.wt still differed between BV positive and negative patients after convariating the effect of gestational age at birth and found to be statistically significant (Table 9).

Incidence of low APGAR at birth among study population
The mean APGAR is 5.133 in BV +ve and 7.45 in BVve women. APGAR is significantly lower (p=0.004) in BV positive patients may be due to preterm delivery, low b.wt and early onset of neonatal sepsis (Table 10).

Incidence of congenital abnormalities in study population
3.33% of BV +ve and 1.7% of BV -ve women had Cong. abnormalities. It did not differ significantly between BV positive and negative patients (Table 11).

Incidence of neonatal jaundice among study population
In the analysis, 50% of BV+ve and 30% of BV -ve had neonatal jaundice. It is significantly found to be more in BV positive women with a p-value of 0.039. But when it is analyzed separately among term and preterm babies in BV positive and negative women, there is no statistically significant difference (p = 0.072) (Table 12).

Incidence of early neonatal sepsis among study population
In the analysis, 13.3% of BV +ve and 4.2% of BV -ve women had early neonatal sepsis. It was significantly associated with BV positive women (Table 13).

Incidence of puerperal sepsis among study population
In the present study, 3.3% of BV +e and 0.8% of BV -ve women had puerperal sepsis. Puerperal sepsis did not differ significantly (p = 0.361) between BV positive and negative women (Table 14).

Mode of onset of labour among study population
In BV +ve women, 60.7% had spontaneous onset of delivery, and 39.2 % were induced. In BV -ve women, 71.5% had spontaneous, and 28.4% were induced. Mode of onset of labour did not differ significantly between BV positive and negative women (Table 15).

DISCUSSION
Bacterial vaginosis is a polymicrobial syndrome and one of the common causes of vaginal discharge, but 50% are asymptomatic. Studies round the world demonstrate that BV in pregnancy is associated with maternal and neonatal morbidity. 7 Preterm delivery is the major cause of perinatal morbidity and mortality. The etiology is multifactorial, but there is now substantial evidence that infection ascending into the uterine cavity from the lower genital tract is associated with idiopathic preterm labour. 8 The incidence varies in different population in different clinical situations. Overall the incidence of BV in antenatal women ranges from 10% -41%. 9 In the present study, the incidence of BV was 20% corresponding to the quoted incidence and correlates with the studies done by Gravett  Various studies have shown that treatment with metronidazole in BV positive pregnant women is associated with a significant decrease in maternal and fetal morbidity. Hence there may be a role for screening BV in pregnancy at booking visit. Clinical criteria along with Gram stain which is a simple procedure can be used for diagnosis instead of sophisticated lab techniques. Early treatment of BV positive individual may reduce the morbidity due to this condition.
Treating BV positive pregnant women at high risk of preterm delivery has now challenged by more recent evidence. The evidence to date suggests that there is no role for antibiotic therapy in low-risk pregnant women who have BV. 10 Given our current knowledge, the treatment of BV in pregnancy or just before conception will be beneficial.

CONCLUSION
Vaginal milieu at various gestational ages is not different. Hence screening for BV at the first trimester of pregnancy is a representative of the vaginal milieu in all trimesters. The clinical method using Amsel's criteria in combination with Gram stain is a simple, inexpensive, easily reproducible, method for diagnosis and can be used on a mass scale. BV in pregnancy is associated with significant risk of preterm labor and PROM. Fetal morbidity in terms of low birth weight, low APGAR and neonatal Jaundice is significantly higher among BV positive pregnant women, and this is possible because of lower gestational age at birth. So, Universal screening of all pregnant women at the booking visit may be recommended to initiate treatment in symptomatic women and those with high risk for preterm delivery.