The placentas of 16 pregnant women found to have Covid-19 during routine testing at a Chicago hospital all showed evidence of injury, indicating that women infected with coronavirus may need close monitoring during pregnancy, researchers said on Friday.
Fifteen of the women delivered healthy babies , while one miscarried. None of the live babies tested positive for Covid-19, the illness caused by the novel coronavirus.
The study, published in the American Journal of Clinical Pathology, found that 12 of the women, or 80%, had a type of injury that can impair blood flow from the mother to the fetus called vascular malperfusion. Six of them, or 40%, had blood clots in the placenta. An historical comparison group showed vascular malperfusion in 55% of patients and placental blood clots in 9% of cases.
The research involved women who gave birth at Northwestern Medicine Prentice Women's Hospital between March 18 and May 5.
"These findings support that there might be something clot-forming about coronavirus, and it's happening in the placenta," Dr. Jeffrey Goldstein, a Northwestern pathologist and study author told Reuters. He said issues with placental blood flow could lead to fetal growth restriction, low levels of amniotic fluid or even fetal demise.
There have been reports of blood clots in adult Covid-19 patients that caused strokes.
In this study, however, none of the 15 live babies appear to have any health problems.
Goldstein said it makes sense to continue to follow babies born to coronavirus-infected mothers to see if they face any difficulties.
The placenta is the first organ to form in fetal development. It acts as the fetus' lungs, gut, kidneys and liver, taking oxygen and nutrients from the mother's blood stream and exchanging waste.