Placentas From Pregnant Women With Coronavirus Show Injury, Abnormal Blood Flow

EVANSTON, Ill. — There’s been a lot of confusion in recent months surrounding whether or not COVID-19 can harm babies still residing in their mother’s womb. Now, a new study from Northwestern University has found some compelling evidence that COVID-19 can, at the very least, interfere in pregnancies.

Placentas taken from 16 women who tested positive for COVID-19 while pregnant were pathologically examined right after birth, and they all showed significant evidence of injury. More specifically, these injuries indicated abnormal blood flow between mother and child. These observations are quite significant, and possibly mean the discovery of a new COVID-19 related complication.

We’re still figuring out the best ways to deal with COVID-19 across different scenarios, and this study may prove invaluable when it comes to properly monitoring and treating COVID-19 positive pregnant women moving forward.

“Most of these babies were delivered full-term after otherwise normal pregnancies, so you wouldn’t expect to find anything wrong with the placentas, but this virus appears to be inducing some injury in the placenta,” says senior author Dr. Jeffrey Goldstein, assistant professor of pathology at Northwestern University Feinberg School of Medicine and a Northwestern Medicine pathologist, in a release. “It doesn’t appear to be inducing negative outcomes in live-born infants, based on our limited data, but it does validate the idea that women with COVID should be monitored more closely.”

How can pregnant women’s placentas be monitored? Non-stress tests are one option. These tests measure how well a placenta is sending oxygen. Meanwhile, growth ultrasounds, which determine if a baby is growing at a normal rate, are another option.

“Not to paint a scary picture, but these findings worry me,” co-author Dr. Emily Miller, assistant professor of obstetrics and gynecology at Feinberg and a Northwestern Medicine obstetrician, comments. “I don’t want to draw sweeping conclusions from a small study, but this preliminary glimpse into how COVID-19 might cause changes in the placenta carries some pretty significant implications for the health of a pregnancy. We must discuss whether we should change how we monitor pregnant women right now.”


“Our study, and other studies like it, are trying to get on the ground floor for this exposure so we can think about what research questions we should be asking in these kids and what can or should we do now to mitigate these same types of outcomes,” notes Dr. Goldstein.

All of the studied mothers but one gave birth during their third trimester (one had a miscarriage during her second trimester).

“That patient was asymptomatic, so we don’t know whether the virus caused the miscarriage or it was unrelated,” Dr. Goldstein explains. “We are aware of four other cases of miscarriage with COVID. The other reported patients had symptoms and three of four had severe inflammation in the placenta. I’d like to see more before drawing any conclusions.”

The placenta is immensely important during pregnancy and serves as the fetus’ lungs, liver, and kidneys; taking in nutrients and oxygen from mom’s blood stream and sending out waste. It also is responsible for many hormonal changes in pregnant women. Essentially, the placenta is considered a record or roadmap of a pregnancy that doctors can examine after the fact to get a better idea of what went on in utero.

“The placenta acts like a ventilator for the fetus, and if it gets damaged, there can be dire outcomes,” Miller says. “In this very limited study, these findings provide some signs that the ventilator might not work as well for as long as we’d like it to if the mother tests positive for SARS-CoV2.”

The placentas collected from COVID-19 positive mothers displayed two main traits: signs of poor blood flow from mother to fetus due to abnormal blood vessels known as maternal vascular malperfusion (MVM), and blood clots in the placenta (intervillous thrombi). Normally, MVM in a pregnant woman is a sign of high blood pressure, but only one of the examined coronavirus positive women had hypertension.

“There is an emerging consensus that there are problems with coagulation and blood vessel injury in COVID-19 patients,” Dr. Goldstein theorizes. “Our finding support that there might be something clot-forming about coronavirus, and it’s happening in the placenta.”

While some of the pregnant women exhibited COVID-19 symptoms and others didn’t, all of their babies were born perfectly healthy.

“They were healthy, full-term, beautifully normal babies, but our findings indicate a lot of the blood flow was blocked off and many of the placentas were smaller than they should have been,” Miller comments. “Placentas get built with an enormous amount of redundancy. Even with only half of it working, babies are often completely fine. Still, while most babies will be fine, there’s a risk that some pregnancies could be compromised.”

The study is published in the American Journal of Clinical Pathology.

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John Anderer

Born blue in the face, John has been writing professionally for over a decade and covering the latest scientific research for StudyFinds since 2019. His work has been featured by Business Insider, Eat This Not That!, MSN, Ladders, and Yahoo!

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