The Vaginal Microbiome in Women of Reproductive Age with Healthy Weight versus Overweight/Obesity

ABSTRACT Objective Evaluate differences between the vaginal microbiome of reproductive-aged women with overweight and obesity (Ow/Ob) compared with healthy weight (HW). Methods A cohort of 367 non-pregnant women (18-40 years) with Ow/Ob (body mass index [BMI] ≥25 kg/m 2 ) was case-matched with 367 women with HW (BMI 18.0-24.9 kg/m 2 ). The study was a secondary analysis of 16S rRNA vaginal microbiome surveys through the Vaginal Human Microbiome Study (VaHMP). Groups were matched on age, race/ethnicity, income, and nulliparity status. Results Mean age and BMI of Ow/Ob and HW groups were 26.8 versus 26.7 years and 37.0 versus 22.1 kg/m 2 , respectively. The overall vaginal microbiome composition differed between groups (PERMANOVA, p=0.035). Women with Ow/Ob had higher alpha-diversity compared with women with HW (Wilcoxon test, Shannon index p=0.025; Inverse Simpson index p=0.026). Lactobacillus dominance (≥30% proportional abundance) was observed in a greater proportion of women with HW (48.7%) compared with Ow/Ob (40.1%; p=0.026). Conclusions The vaginal microbiome differs in reproductive-aged women with Ow/Ob compared with women with HW, with increased alpha-diversity and decreased predominance of Lactobacillus . Observed differences in vaginal microbiome may partially explain differences in preterm birth and bacterial vaginosis risk between these populations.