During pregnancy, women experience changes in the microbiome, the community of bacteria that lives inside and on the body that plays an important role in maintaining health and fighting diseases.

Microbiome Changes During Pregnancy

Earlier studies have found that changes in the microbiome in pregnant women is partially responsible for their weight gain and essential inflammatory response.

A study published earlier this month also found an association between microbiome in newborns' poop and their risk for weight problems by age 3.

Researchers now find evidence showing that intestinal bacteria appear to "sense" pregnancy and assist the baby in breaking down sugar in mother's milk.

In a new study published in Cell Reports on April 16, researchers found that the progesterone, a hormone that plays a role in menstrual cycle and in maintaining the early stages of pregnancy, regulates the composition of bacteria during gestation in a way that can help the development of the baby.

Bifidobacterium

Omry Koren, from the Bar-Ilan University, and colleagues studied changes in bacteria as pregnancy progressed and found dramatic changes in the composition of bacteria during pregnancy, which include an increase in the abundance of Bifidobacterium.

Bifidobacterium are crucial for babies because these metabolize the healthy sugars present in breast milk that help in infants' growth. These bacteria also have probiotic capabilities. Earlier studies have found that preterm delivery may occur when Bifidobacterium does not increase during pregnancy.

Bifidobacterium Senses Progesterone

The researcher imitated pregnancy in mice using progesterone and found an increase in the level of Bifidobacterium in the animals. They also found that the bacteria rapidly increased when progesterone is administered in vitro.

The findings suggest that Bifidobacterium senses progesterone and then responds to it.

"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," the researchers wrote in their study.

"Using in-vivo-transplanted pellets, we found that progesterone, the principal gestation hormone, affects the microbial community."