What We Know About The Link Between Fever During Pregnancy And Autism

Having a fever during pregnancy could raise the risk of having a child with autism-spectrum disorder by 34 percent, according to a study published Tuesday in the journal Molecular Psychiatry. For women who experience three or more fevers after the 12th week of pregnancy, that risk could be even higher.

“We think what’s going on is inflammation associated with infection, which is reflected by fever, results in changes in the way the brain develops,” said Dr. W. Ian Lipkin, study author and director of the Center for Infection and Immunity at Columbia University’s Mailman School of Public Health.

“As a fetus develops, different organ systems, and even different portions of the brain, come online,” Lipkin said. A strong immune response from the mother could interrupt that development.

The researchers used data from the Autism Birth Cohort Study on more than 95,000 children born in Norway between 1999 and 2009. Of those children, 583 developed an autism-spectrum disorder, and 16 percent of mothers in the study reported having a fever during pregnancy. 

Fever during pregnancy is relatively common. About 20 percent of women in the United States report one or more fever episodes while pregnant, according to one study. About 1 in 68 children in the U.S. has an autism-spectrum disorder. 

Still, lead study author Dr. Mady Hornig cautioned that many children who developed autism in the recent study had mothers who didn’t report fever during pregnancy. 

“It’s really just a risk factor,” said Hornig, an associate professor of epidemiology at Columbia University Medical Center. “By far the great majority of women [who develop fever during pregnancy] do not have children with autism.”

The study also examined whether taking anti-fever medicine, such as acetaminophen and ibuprofen, could reduce autism risk. Researchers found that women who took acetaminophen for fever in their second trimester minimally reduced their risk, which could point to an area ripe for future study.

“If we know better ways to manage fever during pregnancy or if we can prevent infection that leads to fever in the first place, that’s also valuable,” Hornig said.

Many different factors have been linked to autism, including genetics and environmental risks. But the new research provides some intriguing clues about the role fever-induced inflammation might play.

“It does make the point that people should probably be vaccinating against influenza, for example, as well as other sorts of infections that might occur during pregnancy,” Lipkin said.

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