New Study Examines Role Of Placenta Bacteria08:27

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A new study, published this week in Science Translation Medicine, tells us more about the role that bacteria may play in the health of a newborn baby.

The study found that the placenta, once thought to be sterile, is actually home to a world of bacteria that help shape the baby's health.

Dr. Kjersti Aagaard of Baylor College of Medicine in Houston, led the study and discusses the findings with Here & Now's Robin Young.

Interview Highlights: Dr. Kjersti Aagaard

On the reason behind studying the placenta

"There were two reasons we were interested in looking in the placenta. First of all, several years ago, we published a study in which we looked in the vaginal microbiome in women who were pregnant, and compared it to non-pregnant women. And we found that, although the vaginal microbiome was different by virtue of being pregnant, none of the microbes we were picking up in that pregnant vaginal microbiome were similar to what other groups were publishing were present in the baby's gut when it was born. And so we were interested in specifically looking at the placenta, because other groups, such as that of Indira Mysorekar at Washington University, had shown that when they looked under a regular microscope, about a third or so of the time, they could see just gross microscopic evidence that showed them that there were bacteria present in completely normal placentas."

On her team's findings

"When we compared 80-some women who'd had pre-term birth to those who'd had term birth and looked at their placental microbiome, we noticed some distinctions between the women who'd delivered pre-term and the women who'd delivered term. Now, this is just an association, meaning that we observed this, but we don't know what potentially causes it or not."

"We observed that the bacteria that were in the placenta were actually most similar to women's oral bacteria. But we also have some other clues that this may be real and potentially related. We've known for several years now that if we treat periodontal disease once it's set in and the pregnancy is established, then we can't impact the rate of pre-term birth. So that would suggest that perhaps these bacteria already within the placenta earlier on, before we can potentially treat the pre-term birth, and would be consistent with what we observed in this study."

On the significance of the placental mircobiome

"We pass onto our kids, between us and their dad, about 23,000 or so genes. But these microbes infuse in about 4,000,000 genes. So we think about the scale in what makes our kids, you know, somewhat like us but so incredibly different, it has to do with probably these interactions between our DNA, our what we call epigenome, where the programmable portion of our DNA [is], and then our microbiome, and how these all fit together is going to be really, really interesting over time to learn more about."


  • Kjersti Aagaard, OB/GYN specializing in the field of maternal-fetal medicine. She is an associate professor at Baylor College of Medicine.

This segment aired on May 22, 2014.