It’s no secret that the body does wonders during pregnancy, getting ready to bring new life into the world in the best possible way. A new Israeli study now found that intestinal bacteria is part of that effort, and even senses and responds to pregnancy hormones.

The research found that during pregnancy the hormone progesterone regulates the microbial composition of bacteria in a way that may help the baby develop, by affecting an increase in bacteria called Bifidobacterium that metabolize the healthy sugars in breast milk.

The study, conducted by Dr. Omry Koren and Prof. Yoram Louzon of Bar-Ilan University, was recently published in Cell Reports.

“Our results delineate a model in which progesterone promotes growth of Bifidobacterium during late pregnancy,” Koren explains.

Dr. Omry Koren of Bar-Ilan University. Photo: courtesy

The researchers studied changes in bacteria as pregnancy progressed and discovered a dramatic change in the composition of bacteria during its late stages, including an increase in Bifidobacterium. When the researchers imitated pregnancy in mice by using progesterone, they again found that Bifidobacterium increased, leading them to believe that Bifidobacterium senses progesterone and reacts to it.

When they administered progesterone in vitro, the researchers found that Bifidobacterium increased rapidly, leading them to conclude that the bacteria does indeed sense and respond to the hormone.

Koren and his team are now attempting to identify how these bacteria react, what genes are turned on, what other pregnancy hormones do and what effect they have.

“The findings provide new insights into understanding the relationship not only between hormones and intestinal bacteria during pregnancy, but also for other conditions in which hormones are involved, such as progesterone supplementation as a component of fertility treatments or therapy in menopausal women,” he says.