It has long been thought that the placenta, which provides oxygen and nourishment to the growing fetus and is involved in the removal of waste products from the baby's blood, is a sterile environment.
Findings of a new study, however, show that the organ contains a community of diverse bacteria known as placental microbiome that serves a crucial role in helping newborns prepare for life outside the womb.
For the study published in the journal Science Translational Medicine on May 21, James Versalovic, from the Department of Pathology and Immunology at the Baylor College of Medicine and Texas Children's Hospital in Houston, and his colleagues collected placental tissues from more than 300 women.
By extracting and sequencing human and bacterial DNA from these samples, the researchers found more than 300 diverse types of bacteria in the placental tissue which include the nondisease-causing strains of E. coli. Versalovic and his colleagues also found that the makeup of these placental microbes differs in women who gave birth prematurely and in women who had full-term delivery. Knowing this could pave way to diagnostic tests that could determine which women are at risk of pre-term delivery.
Versalovic said that the bacteria in the placenta may be protecting and helping the baby as there was difference in the placental microbiome of women who gave birth at full term and those who gave birth before their due date. Exposure of the developing fetus to this microbiome, Versalovic said, may have crucial effects on the baby's early development.
"This intimate relationship has resulted in the maintenance of a microbial community in the placenta during healthy pregnancies that clearly is not impacting the fetus in a negative way and may be helping to nourish the fetus, protect the fetus, enable the fetus to develop," Versalovic said.
The researchers also found that the bacteria in the placenta were more like those found in the mouth rather than in the vagina, skin or gut. They believe that the microbes may have gotten to the placenta after entering the bloodstream from the mother's mouth when she brushes her teeth, which highlights the importance of taking good care of the mouth and teeth during pregnancy.
"This re-emphasizes the importance of oral health during pregnancy," said study author Kjersti Aagaard, from the Baylor College of Medicine. "Women may need to pay attention to their teeth even before they may become pregnant, because the placenta develops early in pregnancy."
