Dr. Omry Koren – Progesterone Increases Bifidobacterium Relative Abundance during Late Pregnancy

Dr. Omry Koren


  • Bifidobacterium abundance increases in the gut during pregnancy in women and mice
  • Progesterone supplementation alters gut microbial composition in mice and in vitro
  • Progesterone supplementation increases Bifidobacterium abundance in mice and in vitro
  • We suggest that progesterone promotes Bifidobacterium growth during late pregnancy


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 invivo-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, including Bifidobacterium, was also demonstrated in vitro, indicating a direct effect. Altogether, our results delineate a model in which progesterone promotes Bifidobacterium growth during late pregnancy.

Graphical Abstract

Read the full article