The vaginal microbiome in women of reproductive age with healthy weight versus overweight/obesity

Abstract

Objective: The aim of this study was to evaluate the differences between the vaginal microbiome of reproductive-aged women with overweight and obesity (Ow/Ob) compared with healthy weight (HW).

Methods: In this case-control study, a cohort of 367 nonpregnant women (18 to 40 years) with Ow/Ob (BMI ≥25 kg/m² ) was case-matched with 367 women with HW (BMI 18.0 to 24.9 kg/m² ). 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/m² , 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 the vaginal microbiome may partially explain differences in preterm birth and bacterial vaginosis risk between these populations.

Figure 1:. Vagitypes in Healthy Weight (HW) versus Overweight/Obesity (Ow/Ob) by Race.

Vagitypes of women in the healthy weight and overweight/obesity groups according to total cohort, African ancestry, and European ancestry. The blue bar identifies vagitypes with Lactobacillus dominance (at least 30% proportional abundance).

Figure 2:. Vaginal Microbiome Diversity Measures in Women with Healthy Weight (HW) versus Overweight/Obesity (Ow/Ob) by Race.

A. Shannon index and Inverse-Simpson Index were significantly different in HW (blue) compared with Ow/Ob (red) considering the entire cohort; B. Among those of African ancestry, alpha-diversity was higher in the Ow/Ob group than in HW; C. In participants of European ancestry, there was no significant difference in alpha-diversity between HW and Ow/Ob groups.

Figure 3:. Heatmap of Taxa Identified in Regularized Logistic Regression Model.

Taxa identified by regularized logistic regression model to have nonzero weights and to be potential contributors of differences between healthy weight (HW) and overweight/obesity (Ow/Ob) cohorts.