Placental microbiome

The placental microbiome is the nonpathogenic, commensal bacteria claimed to be present in a healthy human placenta and is distinct from bacteria that cause infection and preterm birth in chorioamnionitis. Until recently, the healthy placenta was considered to be a sterile organ but now genera and species have been identified that reside in the basal layer.

It should be stressed that the evidence for a placental microbiome is controversial. Most studies supporting the existence of a placental microbiome lack the appropriate experimental controls, and it has been found that contamination is most likely responsible for reports of a placental microbiome.

The placental microbiome more closely resembles that of the oral microbiome than either the vaginal or rectal microbiome.