Microbes found in the placenta are unexpectedly closely related to bacteria in the mouth, and could influence whether pregnant women give birth prematurely, researchers say.
Scientists had long thought the placenta was sterile, free of bacteria and other microbes. However, last year, researchers discovered healthy placentas actually harbor microbial communities, or microbiomes.
"For every pound of placental tissue, there is approximately 1 gram of microbial DNA," said lead study author Dr. Kjersti Aagaard, an obstetrician-gynecologist and maternal-fetal medicine specialist at the Baylor College of Medicine and Texas Children's Hospital in Houston. (There are about 453 grams in 1 pound.)
A host of microbes lives on and in the human body, for example, in the gut, mouth and genitals; these bacteria are often friendly, helping the body live. Aagaard and her colleagues recently analyzed the vaginal microbiome during pregnancy and noted "that the most abundant microbes in the mom's vagina were not what populated the baby's intestinal microbiome. We reasoned that there must be another source seeding the infant's gut at birth, so we sought to examine the placenta."