First trimester bacterial vaginosis, individual microorganism levels, and risk of second trimester pregnancy loss among urban women

ObjectiveTo examine the role of first trimester bacterial vaginosis (BV) and level of BV-associated microorganisms, diagnosed using the Nugent gram stain criteria and the risk of second trimester pregnancy loss among urban women.DesignProspective cohort study.SettingUrban prenatal care clinics.Patient(s)Women presenting for their first prenatal care visit who had completed 12 weeks gestation or less and resided within Philadelphia, Pennsylvania.Main Outcome Measure(s)Pregnancy loss.Result(s)Of 1948 women enrolled at a mean gestational age of 10 weeks (range 7.4 to 12.6 weeks), those with the highest level of BV-related vaginal flora alteration compared with women with normal vaginal flora had over a twofold increased risk of second trimester pregnancy loss after adjustment for confounders (adjusted hazard ratio [aHR] 2.49, 95% confidence interval [CI] 1.13 to 5.48). Low Lactobacillus spp. and the absence of Lactobacillus spp. were also significantly related to the risk of second trimester pregnancy loss (aHR 1.32, 95% CI 1.10–1.64; aHR 2.30, 95% CI 1.09–4.85; respectively).Conclusion(s)Overall BV positivity was not related to second trimester pregnancy loss. Comparing the highest to lowest tertile of BV positivity in early pregnancy conferred a two-fold increased risk of second trimester pregnancy loss and low amounts or the absence of Lactobacillus spp. in the first trimester also significantly increased the risk of second trimester pregnancy loss.