Researchers say Covid infection during pregnancy is tied to autism — but they aren’t yet sure why

Children whose mothers got Covid while pregnant are at an increased risk of autism and other developmental disorders and delays, researchers have found.

The Massachusetts General Hospital-Brigham researchers said those children faced an elevated risk of speech delays and motor disorders — although the connection remains unclear for now and the findings don’t prove the virus causes the conditions.

The new observational study examined the health of over 18,000 mothers and their children during the early years of the pandemic, finding that Covid infection during pregnancy was associated with 29 percent higher odds of kids developing a neurodevelopmental condition by the time they turned three years old.

Some 16 percent of the 861 children whose mothers had Covid during their pregnancy received a neurodevelopmental diagnosis, the analysis showed, compared with just 9.7 percent of the 1,680 whose mothers were not infected.

The risk was also found to be higher in male babies than in females, as well as during the third trimester of pregnancy. Previous research has suggested male fetal brains are more susceptible to maternal immune responses.

“These findings highlight that Covid-19, like many other infections in pregnancy, may pose risks not only to the mother, but to fetal brain development,” Dr. Andrea Edlow, a Maternal-Fetal Medicine specialist at the health system, explained in a statement.

“They also support the importance of trying to prevent Covid-19 infection in pregnancy and are particularly relevant when public trust in vaccines — including the Covid-19 vaccine — is being eroded.”

Declining trust in vaccines

Trust in vaccines has been declining in the U.S. over the last few years, with significant downturns in perceptions of safety for seasonal flu, measles-mumps-rubella and Covid vaccines, according to a report from the University of Pennsylvania’s Annenberg Public Policy Center.

Only 66 percent of those surveyed believed the benefits of the Covid shot outweigh the risks, despite evidence suggesting that Covid vaccines are more effective than seasonal flu vaccines.

A study published earlier this month even found that receiving the vaccine prolonged the life of some cancer patients.

Pregnant women who get vaccinated against Covid pass that protection along to their infants.

But pregnant patients who have Covid are at a higher risk of bad outcomes, Dr. Neil Silverman, a professor of clinical obstetrics and gynecology at UCLA, told NPR last May.

“No matter what the politics say, the science is the science, and we know that objectively, pregnant patients are at substantially increased risk of having complications,” Silverman said.

Maternal infection and autism

Whether those complications include autism has been up for debate.

Two recent studies from researchers in New York said pandemic-era babies were not at an increased risk of the disorder and that there was no evidence that maternal sickness during pregnancy causes autism. Instead, the researchers cited unique, pandemic-related environmental factors that could have caused stress and other changes.

Still, Covid isn’t the only viral infection that’s been linked with the risk for a range of neurodevelopmental diseases during childhood.

The flu has been tied to a child’s risk for both autism and schizophrenia — and researchers have pinpointed an apparent reason: proteins called cytokines that regulate our immune systems.

The cytokines may affect the placenta and even reach the fetus.

“There’s no doubt from the animal models that there is a link between maternal immune activation, changes in gene expression in the brain, changes in brain development and long-lasting changes in behaviors,” Kim McAllister, who directs the Center for Neuroscience at the University of California Davis, told NPR in 2023.

The takeaway

Whether cytokines are responsible for this heightened fetal risk in Covid patients is still a question.

What isn’t a question is how bad last year’s flu season was: the worst flu season in the U.S. in 15 years.

Similar to the Covid vaccine, experts say a flu shot can help to protect both the mother’s and baby’s health. However, breakthrough infections do occur, though they’re usually less severe.

So, just how concerned should expectant parents be?

“The overall risk of adverse neurodevelopmental outcomes in exposed children likely remains low,” Dr. Roy Perlis, of the Mass General Brigham Department of Psychiatry, said.