What Your Placenta Has in Common with Your Mouth

New research uncovers some fascinating facts about the placenta.

woman holding her pregnant belly Gia Canali

While we once thought of the placenta as a sterile environment, it turns out the baby-nourishing organ contains a whole microenvironment of bacteria—one that resembles your mouth, according to research published in Science Translational Medicine. Cool, huh?

When researchers looked at 320 placentas, they found that 10 percent of the placenta is made of up 300 different kinds of bacteria. This bacteria goes on to make up your baby's microbiome, a collection of trillions of microorganisms, like bacteria, that support the immune and digestive systems.

This study is a step in uncovering bacteria's role in pregnancy, explains Kjersti Aagaard, M.D., Ph.D., associate professor in the department of obstetrics and gynecology at the Baylor College of Medicine, and author of the study. As we gain more understanding of how the placenta's biology changes, we'll be able to speculate how bacteria contributes to pregnancy, she adds.

Here are some interesting implications of her findings:

The study found that the bacteria levels of full-term placentas were different from those of pre-term placentas, suggesting that bacteria may play a role in pre-term births. The research is still too preliminary to confirm the link, but this knowledge could potentially help researchers prevent preterm births in the future. (In the meantime, here are some proven ways to help prevent a premature birth.)

So, while interesting, this research is just too early to take advice from—but it can provide some comfort if you end up needing a C-section. Here's why: Conventional thinking was that children delivered via C-section were missing out on the bacteria in the birth canal, which is said to help shape a child's immune system. But since the placenta may expose the fetus to healthy bacteria, being born via C-section may present less of a problem for the baby than originally thought, says Dr. Aagaard.