Perceived Stress and Molecular-BV in the NIH Longitudinal Study of Vaginal Flora.

Vaginal microbiota provide the first line of defense against urogenital infections primarily through protective actions of Lactobacillus spp. Perceived stress increases susceptibility to infection through several mechanisms, including suppression of immune function. We investigated if stress was associated with deleterious changes to vaginal bacterial composition in a subsample of 572 women in the Longitudinal Study of Vaginal Flora, sampled from 1999 through 2002. Using Cox proportional-hazard models, both unadjusted and adjusted for sociodemographics and sexual behaviors, participants who exhibited a 5 unit-increase in Cohen's perceived stress scale had greater risk (aHR=1.40, 95% CI 1.13-1.74) of developing molecular bacterial vaginosis (BV), a state with low Lactobacillus abundance and diverse anaerobic bacteria. A 5-unit stress increase was also associated with greater risks for transitioning from the L. iners-dominated community state type (26% higher) to molecular-BV (aHR=1.26, 95% CI 1.01-1.56) or maintaining molecular-BV from baseline (aHR=1.23, 95% CI 1.01-1.47). Inversely, women with baseline molecular-BV reporting a 5-unit stress increase were less likely to transition to microbiota dominated by L. crispatus, L. gasseri, or L. jensenii (aHR=0.81, 95% CI 0.68-0.99). These findings suggest psychosocial stress is associated with vaginal microbiota composition, inviting a more mechanistic exploration of the relationship between psychosocial stress and molecular-BV.