Placenta Home to Diverse Bacteria That May Affect Newborn

The placenta that nourishes the fetus isn’t the sterile environment it was once thought to be, according to a study that finds the organ contains a diverse community of bacteria that affect a newborn’s health.

The study of 320 placentas, published yesterday in the journal Science Translational Medicine, suggests the varied colony of bacteria may influence the pregnancy as well. The analysis by researchers from Baylor College of Medicine in Houston also found a link between the types of bacteria and preterm birth.

As a result of the Human Microbiome Project scientists are increasingly focusing on the thousands of microbes and their genes that make humans their home for new understanding of health and disease. It’s been unclear until now, however, as to when the infant’s microbiome takes shape. Previous studies have shown that newborns develop complex microbial communities in their guts within the first week that fluctuate until a balance is reached at about 1 to 3 years.

“We think this may be early evidence that the infant microbiome is populated before birth,” said Kjersti Aagaard, an associate professor of obstetrics and gynecology at Baylor College of Medicine and a study author. “We don’t have direct evidence but it suggests that.”

Aagaard said the bacteria from the mouth may slip into the bloodstream and into the placenta. Previous research has found an association between pregnant mothers with periodontal disease and preterm birth, she said by telephone.

One surprise finding revealed that in women who had a urinary tract infection during their pregnancy, evidence of the bacteria was found in the placenta even if the infection had been cleared months earlier, she said.

“As a practicing maternal-fetal medicine specialist, it makes me mindful of whole body health for women,” Aagaard said.

Researchers said they plan to further study the connection between placental microbiome and preterm birth in a study of 500 women.

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