Treatment for Bacterial Vaginosis did not significantly reduce preterm birth rates: JAMA

Bacterial vaginosis (BV) is a common condition caused by an overgrowth of normal vaginal flora. Most commonly, this presents clinically with increased vaginal discharge that has a fish-like odor and pregnant women have an increased risk of early delivery. Molecular diagnosis of BV is now available. Its impact in the screening and treatment of BV during pregnancy on preterm births has not been evaluated to date.

In a recent randomized clinical trial AuTop, pregnant women enrolled before 20 weeks’ gestation were assigned to screen and treat or usual care, the preterm birth rate was 3.8% and 4.6%, respectively, which suggests treating for bacterial vaginosis did not reduce the risk of preterm birth. The findings of the study are published in JAMA Pediatrics.

The AuTop trial was a prospective, multicenter, parallel, individually randomized, open-label, superiority trial conducted in 19 French perinatal centers. Low-risk pregnant women before 20 weeks’ gestation without previous preterm births or late miscarriages were enrolled. Participants were randomized 1:1 to BV screen and treat using self-collected vaginal swabs (n = 3333) or usual care (n = 3338). BV was defined as Atopobium vaginae (Fannyhessea vaginae) load of 108 copies/mL or greater and/or Gardnerella vaginalis load of 109 copies/mL or greater, using point-of-care quantitative real-time polymerase chain reaction assays. The control group received usual care with no screening of BV. Overall rate of preterm birth before 37 weeks’ gestation and total costs were calculated in both groups. Secondary outcomes were related to treatment success as well as maternal and neonate health. Post hoc subgroup analyses were conducted.

The key findings of the study are

• Among 6671 randomized women, the intention-to-treat analysis of the primary clinical and economic outcomes showed no evidence of a reduction in the rate of preterm birth and total costs with the screen and treat strategy compared with usual care.

• The rate of preterm birth was 3.8% (127 of 3333) in the screen and treat group and 4.6% (153 of 3338) in the control group (risk ratio [RR], 0.83; 95% CI, 0.66-1.05; P = .12).

• On average, the cost of the intervention was €203.6 (US $218.0) per participant, and the total average cost was €3344.3 (US $3580.5) in the screen and treat group vs €3272.9 (US $3504.1) in the control group, with no significant differences being observed.

• In the subgroup of nulliparous women (n = 3438), screen and treat was significantly more effective than usual care (RR, 0.62; 95% CI, 0.45-0.84; P for interaction = .003), whereas no statistical difference was found in multiparous (RR, 1.30; 95% CI, 0.90-1.87).

The researchers concluded that “In this clinical trial of pregnant women at low risk of preterm birth, molecular screening and treatment for BV based on A vaginae (F vaginae) and/or G vaginalis quantification did not significantly reduce preterm birth rates. Post hoc analysis suggests a benefit of screen and treat in low-risk nulliparous women, warranting further evaluation in this group.”

Reference: Bretelle F, Loubière S, Desbriere R, et al. Effectiveness and Costs of Molecular Screening and Treatment for Bacterial Vaginosis to Prevent Preterm Birth: The AuTop Randomized Clinical Trial. JAMA Pediatr. Published online July 17, 2023. doi:10.1001/jamapediatrics.2023.2250.