(USA TODAY) -- Pregnant women who come down with a fever, especially in the second trimester, have an increased risk of having a baby with autism, a new study reports.
Research published Tuesday by Columbia University’s Mailman School of Public Health observed 95,754 Norwegian children born between 1999-2009. About 15,700 children where born to mothers who had fevers during their pregnancies. Within that group, researchers identified 583 cases of autism spectrum disorder.
Autism risk increased by 34% when mothers reported a fever over 99 degrees at any time during pregnancy. The risk was 40% when fevers occurred in the second trimester. Women who reported having three or more fevers after the twelfth week of pregnancy, increased autism chances for their child by more than 300%.
Mothers who took ibuprofen for fevers did not have children with autism. But, the sample size of those women was so small researchers could not draw any specific conclusions about the drug's effect.
"Future work should focus on identifying and preventing prenatal infections and inflammatory responses that may contribute to autism spectrum disorder," said senior author W. Ian Lipkin, John Snow Professor of Epidemiology and director of the Center for Infection and Immunity, in a statement.
The link between maternal fevers and autism has been documented before, but this study, published in the journal Molecular Psychiatry, is more expansive than past research.
While a single cause of autism isn’t known, previous research has identified other autism risk factors, such as children born to older parents, babies born prematurely or at a low birth weight and second-born children who were conceived less than a year from firstborn children.
About one in 68 children are on the autism spectrum, according to estimates from the Centers for Disease Control’s Autism and Developmental Disabilities Monitoring Network.