Probiotic supplementation during pregnancy for vaginal microbiota improvement and pathogen clearance: A systematic...

Pregnancy is associated with susceptibility to vaginal dysbiosis, including Group B Streptococcus (GBS), bacterial vaginosis (BV), and vulvovaginal candidiasis (VVC). Probiotic supplementation has emerged as a potential strategy to restore vaginal microecology, yet its effectiveness during pregnancy remains uncertain.

To evaluate whether probiotic supplementation during pregnancy increases the likelihood of clearance of GBS colonization, BV, and VVC. We systematically searched PubMed, Embase, Cochrane CENTRAL, and Web of Science from inception to 16 April 2025. Eligible studies were randomized or non-randomized studies comparing probiotic supplementation with placebo or no treatment in pregnant women, reporting outcomes related to vaginal microbiota, pathogen decolonization, or infection resolution. Two reviewers independently screened studies and extracted data. Randomized controlled trials (RCT) were evaluated using the Cochrane ROB-1 tool, and the single non-RCT was assessed using ROBINS-I. Meta-analyses were performed for co-primary outcomes, with subgroup analyses by timing, comparator type (placebo-controlled vs. no-treatment control), and duration of intervention.

Eighteen studies (n = 3705) were included. For the co-primary outcomes, a statistically significant increase in the odds of GBS decolonization was observed (OR 1.38, 95% CI 1.08-1.76; I² = 2%). This association was no longer statistically significant in analyses restricted to RCTs (OR = 1.28, 95% CI 0.93-1.76; I² = 9%) and remained non-significant when further restricted to placebo-controlled RCTs (OR = 1.32, 95% CI 0.94-1.85; I² = 31%). No significant effects were found for BV (OR 0.91) or VVC (OR 0.65). An exploratory pooled analysis across infection types showed no significant overall improvement in infection clearance (OR 1.13, 95% CI 0.94-1.36; I² = 16%). Subgroup analysis indicated greater efficacy in interventions initiated during the third trimester or lasting ≤4 weeks, though interaction tests were not significant.

Probiotic supplementation during pregnancy may increase the likelihood of GBS decolonization. However, this association was not statistically significant in sensitivity analyses restricted to randomized and placebo-controlled trials. No consistent benefit was observed for BV or VVC. Standardized probiotic regimens and harmonized diagnostic frameworks are needed.