Effect of probiotics on vaginal health in pregnancy. EFFPRO, a randomized controlled trial

Preterm delivery is a leading cause of neonatal morbidity and death. It often results from chorioamnionitis, which is a complication of bacterial vaginosis. Probiotics are effective in the treatment of bacterial vaginosis in women who were not pregnant; studies in pregnant woman are missing.

The purpose of this study was to evaluate whether an oral probiotic food supplement supports the maintenance or restoration of a normal vaginal microbiota during pregnancy.

We conducted a randomized, placebo-controlled, triple-blind, parallel group trial. Oral Lactobacillus rhamnosus GR-1and L reuteri RC-14 (10⁹ colony-forming units) or placebo were administered for 8 weeks to women with <12 completed weeks of pregnancy. Participants were enrolled at Tuebingen University Hospital and 10 recruiting gynecologic practices. Vaginal swabs were taken before and after intervention and analyzed according to the Nugent scoring system. Telephone interviews were performed before and after intervention and after delivery. Primary outcome was the proportion of swabs with normal Nugent score (<4) after intervention, compared by Fisher's exact test in an intention-to-treat analysis.

Three hundred twenty pregnant women were enrolled. Vaginal swabs were analyzed from 290 women before and 271 women after intervention. The proportion of normal vaginal microbiota decreased from 82.6 to 77.8% in the treatment group and from 79.1 to 74.3% in the placebo group, with no significant difference across groups after intervention (P=.297).

Oral probiotics may be suitable for implementation in antenatal care but, as administered here, had no effect on vaginal health during mid gestation. Other application routes or probiotic preparations may be more effective in supporting vaginal microbiota during pregnancy.