FIGURE 5.

(A) Dynamics of vaginal microbiome in response to female sex hormones. The surge of estrogen and progesterone causes an increased deposition of glycogen on vaginal epithelial walls. Since glycogen serves as a nutrient source for vaginal microbes, the excess amount of glycogen causes a sudden rise in the numbers of glycogen-degrading, lactic-acid producing Lactobacilli. The concomitant release of lactic acid, along with hydrogen peroxide by Lactobacilli inhibits the growth of other microbes. (B) Trends of log-normalized vaginal hormone levels and Shannon–Weiner Diversity Index of vaginal microbiome across all reproductive and post-reproductive stages of women. The values of estrogen and progesterone across all reproductive and post-reproductive stages of women were collated from various literature sources. The Shannon–Weiner Diversity values and the collated hormone values are log-normalized and plotted together. The stages having sudden perturbations in the hormone levels (onset of puberty, i.e., Tanner stage II, menstrual, onset of pregnancy, i.e., 1st trimester) are observed to have a highly diverse vaginal microbiome. On the contrary, other stages are observed to have stable, less diverse vaginal microbiome.