The placenta has no microbiome

Abstract

Healthy human placentas do not harbor a population of microorganisms, and recent reports that concluded otherwise were likely the result of contamination, according to the largest study of the issue to date (Nature 2019, DOI 10.1038/s41586-019-1451-5). Placental microbes are therefore not associated with common pregnancy complications such as low birth weight. A team co-led by Stephen Charnock-Jones, a reproductive biologist at the University of Cambridge, sequenced the DNA from more than 500 placenta samples to determine whether they could detect a placental microbiome, and if so, link the microbes to pregnancy outcomes. In one series of experiments, they sequenced DNA from 80 placental samples using two techniques. “If there’s a real signal with your sample, you should detect it with both methods,” Charnock-Jones says. But for the most part, the researchers didn’t. Only one bacterium, Streptococcus agalactiae, came up with both techniques, in very small quantities and in just a