Probiotics Reduce Group B Streptococcus (GBS) Colonization During Pregnancy: A Systematic Review and Meta-Analysis

BackgroundTransfer of Streptococcus agalactiae, or Group B Streptococcus (GBS) from parent to newborn during delivery can produce life-threatening infections in neonates. Probiotics could potentially prevent GBS colonization in pregnant individuals. We conducted a systematic review and meta-analysis to evaluate the effectiveness of probiotic administration in treating Group B Streptococcus colonization. MethodsMEDLINE, ClinicalTrials.gov, PROSPERO, and the Cochrane, Wild Card, Central Register of Controlled Trials were searched from the July 2015 of each database until July 2025 that completed a randomized controlled trial which compared Probiotic versus control. We utilized the Cochrane Risk of Bias 2.0 (RoB 2) tool to assess bias in the systematic review. Results14 randomized controlled clinical trials met our inclusion criteria. The trials used oral probiotic administration compared to either a placebo or a control group. A meta-analysis showed that probiotic administration produced a statistically significant decrease in the rate of GBS colonization in pregnant individuals. The individual studies ranged from four showing great effectiveness, while the other 10 studies showed a range of effectiveness, from partially effective to no effectiveness in preventing GBS colonization. ConclusionOverall, probiotics were effective in lowering infection rates of GBS, but individual studies showed great variability. Probiotics show promise in decreasing GBS colonization in pregnant people, but more studies need to be performed in order to use them effectively and decrease antibiotic usage.