Among pregnant women, the coronavirus can severely damage the placenta, leading to fetal asphyxiation and stillbirth, according to research published Feb. 10 in the Archives of Pathology & Laboratory Medicine.
The research team evaluated placentas from 68 perinatal deaths (64 stillbirths and four neonatal deaths) from 12 countries to better understand how COVID-19 may lead to perinatal death. All of the expecting mothers in the study had COVID-19 at some point during their pregnancies and were unvaccinated.
Researchers found 77 percent of the placenta had been destroyed on average among the 68 cases.
"We have never seen this level of destruction from an infectious illness before. It rendered the placenta unfit to carry out its duties," David Schwartz, MD, lead study author and perinatal pathologist in Atlanta, told NBC News. "These fetuses and newborns died from asphyxiation due to lack of oxygen."
Researchers referred to the process of placental destruction as SARS-CoV-2 placentitis, which can happen over days to two weeks. It involves a buildup of the protein fibrin, which causes clotting in the placenta's vascular system, cell death in the organ's protective cell layer, and abnormal inflammation in the placenta.
In November, a CDC report found that while rare, pregnant women who contract COVID-19 are at slightly higher risk for stillbirth compared to uninfected women.
The findings underscore the importance of vaccination among pregnant women, according to health experts.