The gut bacteria residing naturally in our digestive tracts have far-reaching effects beyond aiding in food digestion. Scientific research has unveiled their involvement in the immune system, mental health, and now, even the growth of a healthy placenta during pregnancy.
Recently, UCLA scientists published a study in Science Advances, demonstrating that mice with depleted gut microbiomes had smaller placentas and underdeveloped placental blood vessels compared to normal mice. These conditions could potentially deprive fetuses of essential nutrients and oxygen. However, when malnourished pregnant mice with reduced microbiomes were given short-chain fatty acids, which are produced by gut microbes, their placentas returned to a normal size.
This discovery highlights that the gut microbiome plays a role in angiogenesis, the formation of new blood vessels, and suggests that metabolites produced by these microbes are crucial for feto-placental development.
Senior author Elaine Hsiao, a UCLA associate professor, emphasized that the gut microbiome’s influence begins even during prenatal life. Earlier research by Hsiao demonstrated its impact on the fetal nervous system.
To explore how gut bacteria affect the maternal-fetal environment, UCLA doctoral student Geoffrey Pronovost led a study involving mice. They observed two groups: one without a microbiome from birth and another with a reduced microbiome due to antibiotics. Mating these mice with males allowed researchers to study placental development.
The team suspected that microbial metabolites in the bloodstream could be the missing link. Compared to mice with normal microbiomes, those with depleted microbiomes had smaller placentas and underdeveloped placental blood vessels. Furthermore, fetuses from microbiome-depleted mothers had altered levels of 27 different metabolites in their blood.
While initial tests with some of these metabolites didn’t enhance placental or fetal growth, attention shifted to short-chain fatty acids. These acids, produced by bacterial fermentation of carbohydrates, were found to promote placental growth when added to the mothers’ drinking water.
Although differences exist between mouse and human gestation, these findings could potentially inform future research and treatment strategies for expectant mothers and their babies.