The placenta may have a way to protect itself and the fetus from infection with SARS-CoV-2, clinicians and scientists have found in a collaborative study.

Noting that human placental tissue can be infected by the virus but transmission to the fetus is low, the US researchers set out to look at the role that might be played by the main receptor for the virus, angiotensin-converting enzyme (ACE)-2.

The team, led by Boston Medical Center, studied 24 women who gave birth between July 2020 and April 2021.

Eight had symptomatic COVID-19 in the second trimester, eight were sick from the virus in the third trimester, and eight were not infected during pregnancy.