Use of Vaginal Probiotics During Pregnancy
Vaginal probiotics are generally safe to use during pregnancy, but current evidence shows they provide no proven benefit for preventing adverse pregnancy outcomes or maintaining vaginal health. 1, 2, 3
Safety Profile
Probiotic supplementation during pregnancy is rarely systemically absorbed in healthy individuals and has not been associated with increased adverse fetal outcomes in meta-analyses and randomized controlled trials conducted during the third trimester. 2
Probiotics are well-tolerated by pregnant women and their children, with no significant safety concerns reported in clinical trials. 2, 4
Probiotics are unlikely to be transferred into breast milk, making them safe for use during lactation as well. 2
Clinical Efficacy Evidence
The highest quality randomized controlled trial (2016) demonstrated that oral probiotics had no effect on maintaining or restoring normal vaginal microbiota during pregnancy. 3 This study of 320 pregnant women found:
The proportion of normal vaginal microbiota decreased similarly in both probiotic (82.6% to 77.8%) and placebo groups (79.1% to 74.3%), with no significant difference (P=0.297). 3
Oral administration of Lactobacillus rhamnosus GR-1 and L. reuteri RC-14 for 8 weeks showed no benefit over placebo. 3
Vaginal Microbiome Changes
The vaginal microbiome naturally varies during the third trimester of pregnancy, with complexity of the microbial network increasing from 32 weeks to delivery. 5
While probiotic supplementation may shift features of the vaginal microbiota and loosen the interaction network, these changes have not translated into clinically meaningful outcomes. 5
Treatment of Bacterial Vaginosis vs. Prophylaxis
For symptomatic bacterial vaginosis in pregnancy, the recommended treatment is metronidazole 500 mg orally twice daily for 7 days—not probiotics. 1 This distinction is critical:
Probiotics have shown efficacy for bacterial vaginosis treatment in non-pregnant women, but studies in pregnant women are lacking. 3
The USPSTF recommends against routine screening for bacterial vaginosis in asymptomatic pregnant women at low risk for preterm delivery (Grade D recommendation). 6
Common Pitfalls to Avoid
Do not confuse normal Lactobacillus colonization with bacterial vaginosis, which requires specific diagnostic criteria (Amsel criteria or Gram stain). 7
Avoid treating asymptomatic vaginal colonization, as antimicrobial treatment may disrupt the normal vaginal microbiome without providing measurable improvement in morbidity or mortality. 7
Do not prescribe antibiotics for normal vaginal flora, as this may lead to antibiotic resistance and disrupt the beneficial microbiome. 7
Clinical Bottom Line
While vaginal probiotics are safe during pregnancy, there is no evidence-based indication for their routine use. 3 If a patient chooses to use them, they are unlikely to cause harm but should not be expected to prevent preterm delivery, bacterial vaginosis, or other adverse pregnancy outcomes. 2, 3 For symptomatic bacterial vaginosis, use evidence-based antibiotic therapy with metronidazole instead. 1