People who catch COVID while pregnant might have a higher likelihood of having a child who is later diagnosed with autism or another neurodevelopmental condition, a new study has found. The results add to previous research showing that, among other factors, infections in general during pregnancy are linked to autism risk for the child. They do not, however, suggest that everyone who has COVID while pregnant will have a child with autism.
“Even though there’s an increased risk for autism and other neurodevelopmental disorders, the absolute risk still remains relatively low, especially for autism,” says study senior author Andrea Edlow, a maternal-fetal medicine specialist at Massachusetts General Hospital, referring to having COVID during pregnancy.
For the study, published Thursday in Obstetrics & Gynecology, Edlow and colleagues looked at electronic health records of more 18,000 births that occurred between March 1, 2020, and May 31, 2021, during the first year of the COVID pandemic. They compared the likelihood of a neurodevelopmental diagnosis in children born to individuals who had a positive COVID PCR test during pregnancy with those who didn’t.
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Of the 861 children born to people who had COVID during pregnancy, 16.3 percent went on to receive a neurodevelopmental diagnosis by age 3 compared with 9.7 percent of the 17,263 children born to people who hadn’t had COVID. The diagnoses included not just autism but also speech and language disorders, motor function disorders, and other conditions. When the researchers controlled for various confounding factors, COVID infection during pregnancy was linked to increased odds of these conditions of nearly 30 percent.
The findings add to a body of evidence—mainly in animals but also in humans—suggesting that various infections during pregnancy, such as influenza or rubella, are linked to a higher risk of having a child with autism or a similar condition. Because SARS-CoV-2 rarely crosses the placenta, scientists hypothesize it’s not the virus itself upping the risk. Rather they suspect immune activation in the pregnant person could be responsible.
The new study and previous animal studies together suggest that many types of maternal infection or inflammation can send a signal to the fetus, affecting its brain development, says Kristina Adams Waldorf, a professor of obstetrics and gynecology and adjunct professor of global health at the University of Washington. Adams Waldorf co-authored a study of 1.7 million people born in Sweden who were followed for up to 41 years that found higher rates of autism and depression in those who had been exposed to an infection in utero.
The strongest associations in the new study were for COVID infection in the third trimester and for male offspring. (The increase in odds was not significant for female offspring.) The third trimester is a critical time for fetal brain development, and boys are diagnosed with autism at higher rates than girls in general.
The study has limitations, however. The researchers did not control for maternal health, says Brian Lee, a professor of epidemiology at Drexel University, who has studied the link between infections during pregnancy and autism. People with worse physical health and mental disorders are more likely to have children with neurodevelopmental conditions and are also more susceptible to severe COVID infections, he says.
The study also didn’t specifically control for vaccination status, although very few individuals had been vaccinated during the study period because the COVID vaccine wasn’t widely available at the time. Previous research has shown that vaccination protects pregnant people—who are more likely to get very sick and die from COVID—and their fetuses from the disease.
The study findings come on the heels of controversial statements made by President Trump and Health and Human Services secretary Robert F. Kennedy, Jr., linking Tylenol (acetaminophen) to autism—which the best available evidence does not support. Numerous studies have also shown that vaccines do not cause autism.
It’s important to note that autism is a complex spectrum of conditions—not all of which cause disabilities—with many contributing factors. Genetics is thought to have the biggest influence, but environmental factors such as infection may also play a role.