Objective: During pregnancy, vulvovaginal infections (VVIs), including abnormal vaginal flora (AVF), bacterial vaginosis (BV), and vulvovaginal candidiasis (VVC), are associated with serious complications and discomfort. We aimed to elucidate the effectiveness of oral probiotics in secondary prevention of VVIs in pregnant women. Study design: A multicenter prospective randomized, double-blind, placebo-controlled trial was conducted at three medical centers between 2016 and 2021. Women who complained of vaginal symptoms with positive smear for AVF/BV and/or candida were treated with antibiotics or an antimycotic agent, respectively. After confirmation of VVI eradiation by repeated vaginal smear, the women were divided into a research group, receiving two capsules/day of oral probiotic formula containing Bifidobacterium bifidum, Bifidobacterium lactis, Lactobacillus (L.) acidophilus, L. paracasei, L. rhamnosus and Streptococcus thermophilus (>6 × 10⁹ CFU/capsule), and a control group, receiving a placebo (two capsules/day) until delivery. At least once a month or following complaints, a vaginal smear was taken to assess vaginal microbiota. If VVIs were found, they were treated with antibiotics/antimycotics, and eradication was assessed by a repeated vaginal smear. Lactobacilli vaginal colonization, including the specific strains from the probiotic capsules, were detected using the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF-MS). The primary outcome was the rate of women who developed VVI during the study period until delivery. Results: Twenty-three and twenty-four women were analyzed in the probiotic and placebo cohorts, respectively. There was no difference in the rate of any VVI between the probiotic and placebo cohorts (16 (67%) versus 11 (48%), respectively; p = 0.19), time until first infection or pregnancy outcomes. The lactobacilli strains that colonized the vagina were similar at baseline and following probiotic or placebo administration. No woman was detected with vaginal colonization of the strains from the capsule, although the probiotics were taken for about 4 months. Conclusions: The oral probiotic product tested in this study did not reduce the recurrence rate of VVIs in pregnant women following eradication.

Background/Objective: This study aimed to investigate the efficacy of oral probiotic supplementation in preventing vulvovaginal infections (VVIs) in pregnant women, specifically focusing on abnormal vaginal flora (AVF), bacterial vaginosis (BV), and vulvovaginal candidiasis (VVC). Methods: A multicenter-prospective-randomized, double-blind, placebo-controlled trial was conducted during 2016–2019. Women with normal vaginal flora (Nugent score < 4 and no candida) were divided into a research group, receiving 2 capsules/day of oral probiotic formula containing Bifidobacterium bifidum, Bifidobacterium lactis, Lactobacillus acidophilus, Lacticaseibacillus paracasei, Lacticaseibacillus rhamnosus, and Streptococcus thermophilus, or a control group, receiving a placebo until delivery. Once a month and following complaints, a vaginal smear was taken to assess vaginal flora. Vaginal colonization with the specific lactobacilli from the probiotic capsules was detected using the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The primary outcome was the rate of women who developed VVI. Results: Forty-nine and fifty-one women were analyzed in the probiotic and placebo cohorts, respectively. There was no difference in the rate of VVI between probiotic and placebo groups (14 (29%) versus 14 (27%), respectively; p = 0.80). No woman had vaginal colonization with lactobacilli from the probiotic capsule. Conclusions: The tested oral probiotic product did not reduce the rate of VVI in pregnant women with normal vaginal flora.