Slowly, scientists are starting to learn about the risks to unborn babies from COVID-19. A study released Thursday sheds more light on the way COVID appears to cause some rare stillbirths.
Unlike some other viruses caught by pregnant women, the coronavirus’ most significant harm to pregnancy may come not from infecting the fetus’ internal organs, but by damaging the placenta. In fact, the placenta can become infected with COVID without the baby showing any signs of infection.
The placenta is an organ that technically belongs to the fetus. It’s attached to the mom’s uterus and feeds oxygen and nutrients to the baby through the umbilical cord.
Stillbirth is rare, even in the pandemic. But the danger from COVID to moms and fetuses is clear enough that the American College of Obstetricians and Gynecologists “strongly recommends” that all pregnant women get vaccinated.
The international study, led by an Atlanta pathologist, found that placentas infected with COVID could sustain so much damage that they stop carrying enough oxygen to the baby. In such cases, the baby would suffocate. The types of damage they found came from sources including increased fibrin, a protein involved in blood clotting, and a rare accumulation of inflammatory cells.
“The surprise in this study - and it was a surprise - was that the average placenta in this study was over 75% destroyed,” said Dr. David Schwartz, lead author of the study. “It’s astonishing.”
The authors wrote that that average level of damage “far exceeds the degree of placental...destruction that is typically seen with other” placenta-related viruses. “At these high levels of placental damage, the placenta cannot function at the level necessary to provide sufficient oxygen and nutrients to the fetus to sustain life.”
Schwartz and his 43 co-authors deliberately sought out placentas that were infected with COVID. They ended up finding COVID-19 infected placentas from 64 stillbirths and four deceased newborns, for a total of 68. Where they had medical records from an autopsy of the child, they didn’t find evidence of other causes of death besides the damage to the placenta. “To the best of our knowledge,” the authors wrote, all the mothers were unvaccinated.
As of the first week in January, 42.2% of pregnant women in the U.S. were fully vaccinated, according to the Centers for Disease Control and Prevention.
Stillbirths are rare, including for women with COVID-19. The CDC’s COVID-19 response team in November reported that women who contracted COVID when they were pregnant suffered stillbirths at more than double the rate of women who did not have the virus. Women without COVID had a stillbirth rate of 0.6%. Women with COVID had a stillbirth rate of 1.3%. The study looked at 1.2 million pregnancies in the first 18 months of the pandemic. The rate was highest during the delta surge.
One insight out of the new paper is that the damage to placentas might happen quickly after infection. So if a pregnant woman catches COVID, it might be warranted to monitor the fetus very closely for two weeks afterward.
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