In a study published in the American Journal of Obstetrics & Gynecology, researchers found that, if a woman is infected by SARS-CoV-2 during her pregnancy, the infection damages the placenta’s immune response to further infections – even if the infection was mild.
“This is the largest study to date of placentas from women who had COVID during their pregnancies,” said Professor Kristina Adams Waldorf, at the University of Washington School of Medicine and senior author of the study. “We were surprised to find that women who had COVID during their pregnancies had placentas with an impaired immune response to new infection.”
This finding, Prof Adams Waldorf added, “was the tip of the iceberg” in how COVID might affect foetal or placental development.
During the early stages of the pandemic, many thought that COVID did not appear to harm the developing foetus because there were so few babies born with COVID infection, she noted.
“But what we’re seeing now is that the placenta is vulnerable to COVID-19, and the infection changes the way the placenta works, and that in turn is likely to impact the development of the foetus,” Prof Adams Waldorf said.
“To date, the studies about how COVID might affect foetal or child development are very limited as the children are still very young,” noted co-author Dr Helen Feltovich, professor at Intermountain Healthcare.
“Our study suggests that babies born to mothers infected with COVID at any point during their pregnancy will need to be monitored as they grow up,” she said.
Studies led by Adams Waldorf have shown that pregnant women who contract COVID have a significantly higher mortality rate than those who do not contract COVID. Other studies have found that pregnant women are more likely to risk hospitalisations or preterm birth, according to the Center for Disease Control and Prevention.
It’s unknown how different COVID variants may affect the mother or foetus, Profs Adams Waldorf and Feltovich agree.
“Studying each of the variants in real time is really challenging because they just keep coming so fast, we can’t keep up,” Prof Adams Waldorf said. “We do know that the COVID Delta variant was worse for pregnant individuals, because there was a spike in stillbirths, maternal deaths and hospitalisations at that time.”
Regardless of the variant, Prof Adams Waldorf stressed taking precautions, such as vaccination and booster shots, limiting social contact a bubble of vaccinated individuals even if it means isolating for the duration of the pregnancy.
“The disease may be mild, or it may be severe, but we’re still seeing these abnormal effects on the placenta,” she said. “It seems that after contracting COVID in pregnancy, the placenta is exhausted by the infection, and can’t recover its immune function.”
In this study, a total of 164 pregnant individuals were studied, consisting of 24 uninfected healthy patients as a control group and 140 individuals who contracted COVID. Both groups delivered at about the same time, 37 to 38 weeks. Preterm birth occurred at nearly three times the rate with the patients with COVID when compared with those without. About 75% of the COVID patients had either asymptomatic COVID or mild symptoms.
Source: University of Washington School of Medicine/UW Medicine
