Progesterone Increases Bifidobacterium Relative Abundance during Late Pregnancy.

Abstract

Gestation is accompanied by alterations in the microbial repertoire; however, the mechanisms driving these changes are unknown. Here, we demonstrate a dramatic shift in the gut microbial composition of women and mice during late pregnancy, including an increase in the relative abundance of Bifidobacterium. Using in-vivo-transplanted pellets, we found that progesterone, the principal gestation hormone, affects the microbial community. The effect of progesterone on the richness of several bacteria species,\xa0including Bifidobacterium, was also demonstrated in\xa0vitro, indicating a direct effect. Altogether, our results delineate a model in which progesterone\xa0promotes Bifidobacterium growth during late pregnancy.