Maternal vitamin A and β-carotene supplementation and risk of bacterial vaginosis: a randomized controlled trial in rural Bangladesh123

Background: Bacterial vaginosis (BV) in pregnancy is linked to preterm birth, but its risk factors are not well understood. Micronutrient deficiencies may be associated with an increased risk of this condition. Objective: We assessed the effect of weekly vitamin A or β-carotene supplementation during pregnancy until 3 mo postpartum on BV risk in rural northeastern Bangladesh. Design: In this cluster-randomized, placebo-controlled trial, 33 clusters (n = 33) were randomly assigned to 3 groups. Women (n = 1812) were examined for BV by using self-administered swabs and the Nugent scoring method in early pregnancy, at 32 wk of gestation, and at 3 mo postpartum. Results: The prevalence of BV in early pregnancy, before supplementation, was 7.6% (95% CI: 6.3%, 9.1%) overall. Neither the prevalence nor the incidence of BV in the third trimester differed by supplement group. However, the prevalence (OR: 0.71; 95% CI: 0.52, 0.98) and incidence (RR: 0.58; 95% CI: 0.41, 0.81) of BV at 3 mo postpartum was lower among women in the vitamin A group (9.1% and 6.7%, respectively) than in the placebo group (12.4% and 11.8%, respectively), but not in the β-carotene group. Both vitamin A and β-carotene reduced the prevalence and incidence of BV at both time points (ie, third trimester and 3 mo postpartum) by 30–40% compared with placebo (all P < 0.05). Conclusions: Weekly vitamin A supplementation reduced the risk of maternal BV in this rural Bangladeshi population. Enhancement of vitamin A status before and during pregnancy may reduce the risk of BV in areas with vitamin A deficiency. This trial is registered at clinicaltrials.gov as NCT00198822.