Scientists across the globe join hands to find out why Covid causes stillbirths


Many unvaccinated pregnant women affected by Covid-19 have delivered stillborn children. What was initially thought to be isolated incidents turned out to be widespread across the globe.

The scientific community was unable to understand the mechanism of the virus and the cause of the stillbirths. So a 44-member international research team came together to observe 64 stillbirth cases and four early neonatal deaths from 12 countries to determine how Covid-19 causes perinatal deaths in unvaccinated mothers.

The findings, published in Archives of Pathology & Laboratory Medicine, showed that the Covid-19 infection destroys the placenta, depriving the fetus of oxygen.

Researchers determined the virus reaches the placenta and causes it to fail by passing through the mother’s bloodstream, a process known as viremia.

“Our study identified placental insufficiency as the root cause for stillbirths in women with Covid-19 during pregnancy,” said Dr David Schwartz, an Atlanta-based pathologist who led the study.

“Among the 68 cases, an average of 77 percent of the placenta had been destroyed and rendered useless for supporting critical fetal needs, resulting in stillbirth or early neonatal death,” he added.

In all the cases studied, researchers found the placentas from infected mothers had a severe abnormality called SARS-CoV-2 placentitis, Dr Schwartz said.

The team also found viral-induced lesions in the placenta blocked maternal and fetal blood flow and oxygen, killing placental tissues and causing “irreparable damage”, the report said.

Further, in almost all cases, an increase was observed in fibrin, a key protein involved with blood clotting, so “massive” that it blocked blood and oxygen flow to the placenta.

All the placentas also showed dead cells made up the major cell barrier between the mother and the fetus, known as trophoblast necrosis.

Another placental complication that may have been caused by the virus was a rare accumulation of inflammatory cells called chronic histiocytic intervillositis, which was seen in 97 percent of cases studied by the international research team.

The researchers assumed that many of the infections were from the Delta variant, and not Omicron.

Although other viral, bacterial and parasitic infections that occur in pregnancy and cause stillbirth travel through the placenta and damage the fetal organs, Schwartz said SARS-CoV-2 appears to stop at the placenta and do the most damage there.

“The placental destruction is so severe that whether or not the fetus becomes infected might be irrelevant,” he said.

Studies have shown that the Covid vaccine is safe and effective for both the expectant parent and baby. The studies have also shown that antibodies from the vaccine can pass through to the fetus and protect the baby from Covid-19 after birth.