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COVID-19 During Pregnancy

Worrisome news: having a COVID-19 infection during pregnancy may be injuring the placenta, even if the pregnant woman has no symptoms (asymptomatic) and the baby appears healthy at birth. The human placenta is the temporary organ that nourishes and maintains the developing fetus during pregnancy. It provides oxygen and nutrients to the baby, and removes waste products.

A small study by doctors at the Feinberg School of Medicine (Chicago, Illinois) examined 16 placentas after babies were born - 15 in the third trimester (all live, healthy babies), 1 in the second trimester (after the fetus died). The placentas of women who were currently infected with COVID-19 or had it earlier in the pregnancy showed abnormal or injured blood vessels, which can result in insufficient blood flow between the mother and developing baby. Two common types of injuries were abnormal blood vessels (maternal vascular malperfusion) and blood clots in the placenta (intervillous thrombi).

The study authors said that pregnant women should therefore be monitored more carefully, perhaps with non-stress tests (to see how well the placenta is delivering oxygen) or ultrasounds to measure growth. The good news is that currently the evidence does not suggest that pregnant women have more severe COVID-19 infections than non-pregnant women.

Also good news is that the 15 babies born in the third trimester appeared healthy and normal weight (only one was pre-term, but healthy), and that at birth all the babies were negative for COVID-19. Thus, they did not get the infection from their mothers during pregnancy.

Excerpts from Science Daily: Placentas from COVID-19-positive pregnant women show injury

The placentas from 16 women who tested positive for COVID-19 while pregnant showed evidence of injury, according to pathological exams completed directly following birth, reports a new Northwestern Medicine study.  

The type of injury seen in the placentas shows abnormal blood flow between the mothers and their babies in utero, pointing to a new complication of COVID-19. The findings, though early, could help inform how pregnant women should be clinically monitored during the pandemic.

"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," said senior author Dr. Jeffrey Goldstein, assistant professor of pathology at Northwestern University Feinberg School of Medicine and a Northwestern Medicine pathologist. "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."

Previous research has found that children who were in utero during the 1918-19 flu pandemic, which is often compared to the current COVID-19 pandemic, have lifelong lower incomes and higher rates of cardiovascular disease. Flu doesn't cross the placenta, Goldstein said, so whatever is causing life-long problems in those people is most likely due to immune activity and injury to the placenta..

Fifteen patients delivered live infants in the third trimester, however one patient had a miscarriage in the second trimester. "That patient was asymptomatic, so we don't know whether the virus caused the miscarriage or it was unrelated," Goldstein said, "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 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. The placenta also is responsible for many of the hormonal changes within the mother's body. Examining a woman's placenta allows a pathologist to follow a retroactive roadmap of a woman's pregnancy to learn what happened to the baby in utero or what could happen to both the mother and the infant after birth.

The placentas in these patients had two common abnormalities: insufficient blood flow from the mother to the fetus with abnormal blood vessels called maternal vascular malperfusion (MVM) and blood clots in the placenta, called intervillous thrombi.

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

The 16 women in the study delivered their babies at Northwestern Medicine Prentice Women's Hospital. All tested positive for COVID-19. Four patients came in with flu-like symptoms three to five weeks before delivery and tested positive for the virus. The remaining patients all tested positive when they came in to deliver. Five patients never developed symptoms, others were symptomatic at delivery.

Between 30 and 40 patients deliver at Prentice daily. The team began testing placentas of COVID-19-positive mothers in early April. Fourteen of the live-born infants in the study were born full term and with normal weights and Apgar scores. One live-born infant was premature.

"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 said. "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."

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