Autism risk tied to fever during pregnancy: study

Children are more likely to develop autism if their mothers had a fever during pregnancy, especially in the second trimester, a new study suggested Tuesday.

The study, led by scientists at the Columbia University and published in the journal Molecular Psychiatry, followed 95,754 children born between 1999 and 2009, including 583 cases of autism identified in Norway through an autism birth cohort study.

Mothers of 15,701 children, or 16 percent, reported fever in one or more four-week intervals throughout pregnancy.

It turned out that autism risk was increased by 34 percent when mothers reported fever at any time during pregnancy, and by 40 percent in the second trimester.

The autism risk was increased by over 300 percent for the children of women reporting three or more fevers after the twelfth week of pregnancy, it said.

"Our results suggest a role for gestational maternal infection and innate immune responses to infection in the onset of at least some cases of autism spectrum disorder," first author Mady Hornig, associate professor of epidemiology and director of Translational Research at the Center for Infection and Immunity (CII) at Columbia University's Mailman School of Public Health, said in a statement.

The study, believed to be the most robust to date to explore the risk of autism associated with fevers across the entire span of pregnancy, also looked at two different types of commonly used anti-fever medications -- acetaminophen and ibuprofen -- to address that risk.

Risks were minimally mitigated among the children of women taking acetaminophen for fever in the second trimester, it said.

It also found none of the children born to mothers who took ibuprofe, a nonsteroidal anti-inflammatory drug, developed autism.

However, researchers could not ascertain whether risk was mitigated due to the extremely small number of women using this particular drug for fever.

Their future work, according to the study, would focus on identifying and preventing prenatal infections and inflammatory responses that may contribute to autism.