Factors Associated with Vaginal Lactobacillus Predominance among African American Women Early in Pregnancy

Background: Vaginal Lactobacillus is considered protective of some adverse reproductive health outcomes, including preterm birth. However, factors that increase or decrease the likelihood of harboring Lactobacillus in the vaginal microbiome remain largely unknown. In this study, we sought to identify risk and protective factors associated with vaginal Lactobacillus predominance within a cohort of pregnant African American women. Materials and Methods: Vaginal microbiome samples were self-collected by African American women (N = 436) during their 8-14th week of pregnancy. Sociodemographic information and measures of health behaviors, including substance use, antibiotic exposure, sexual practices, frequency of vaginal intercourse, and the use of vaginal products, were collected through participant self-report. The V3-V4 region of the 16S rRNA gene was targeted for amplification and sequencing using Illumina HiSeq, with bacterial taxonomy assigned using the PECAN classifier. Univariate and a series of multivariate logistic regression models identified factors predictive of diverse vaginal microbiota or Lactobacillus predominance. Results: Participants who used marijuana in the past 30 days (aOR 1.80, 95% CI 1.08-2.98) were more likely to have diverse non-Lactobacillus-predominant vaginal microbiota, as were women not living with their partners (aOR 1.90, 95% CI 1.20-3.01). Cohabitating or marijuana usage were not associated with type of Lactobacillus (non-iners Lactobacillus vs. Lactobacillus iners) predominance (aOR 1.11, 95% CI 0.52-2.38 and aOR 0.56, 95% CI 0.21-1.47, respectively). Conclusions: Living with a partner is conducive to vaginal Lactobacillus predominance. As such, cohabitation may be in important covariate to consider in vaginal microbiome studies.