Women who develop fevers while pregnant may be more than twice as likely to have a child with autism spectrum disorder or another developmental delay, a new study suggests.

Exactly how, or even if, fevers may increase the risk for autism is unknown, and experts were quick to say women should not panic if they do develop a fever while pregnant because taking fever-reducing medications cuts the risk.

One in 88 children in the United States has an autism spectrum disorder, according to the U.S. Centers for Disease Control and Prevention. This is an umbrella term for developmental disorders that can range from mild to severe and that often affect social and communication skills. Little is known about what causes autism or precisely why rates seem to be increasing.

Researchers from the University of California, Davis asked the moms of about 1,100 kids with and without autism spectrum disorder or other developmental delays whether they had the flu or fever during their pregnancies and if they took any medications to treat these illnesses. Their findings were published online in the Journal of Autism and Developmental Disorders.

According to the new data, moms who had a fever from any cause during pregnancy were more than twice as likely to have a child with autism or another developmental delay, when compared with moms who did not run fever during pregnancy. Moms who had the flu during pregnancy were not at greater risk for having children with autism or another developmental delay.

What’s more, moms who took fever-reducing medication during pregnancy had similar risks as those moms who did not run a fever during their pregnancy.

“Our study provides strong evidence that controlling fevers while pregnant may be effective in modifying the risk of having a child with autism or developmental delay,” study author Dr. Ousseny Zerbo, a postdoctoral researcher with Kaiser Permanente’s Northern California Division of Research in Oakland, Calif., said in a university news release. Zerbo was a doctoral candidate with UC Davis when the study was conducted. “We recommend that pregnant women who develop fever take anti-[fever] medications and seek medical attention if their fever persists.”

The findings are culled from the Childhood Autism Risks from Genetics and Environment (CHARGE) study. This is the same dataset that recently led to a report that moms who are obese or have diabetes may be at higher risk for having children with autism. The common denominator between diabetes, obesity and fever is inflammation.

“This study puts the spotlight on inflammatory factors as a possible role in autism,” said Dr. Y. Jane Tavyev, director of pediatric neurology at pediatric services at Cedars Sinai in Los Angeles. But, she added, “I don’t think that this should make people panic about getting sick during pregnancy. Mounting a fever is part of the body’s immune response to help kill bacteria and viruses.”

Dr. Daniel Coury, a professor of clinical pediatrics and psychiatry at Ohio State University and Nationwide Children’s Hospital in Columbus, Ohio, urges caution in interpreting the new findings. “It is an association, and doesn’t mean that maternal fever causes autism, just that we see these two occurring together more frequently than other things.”

Alycia Halladay, director of research for environmental sciences at Autism Speaks, said that “this new report from the CHARGE study adds another piece to the puzzle around environmental risk factors in the causes of autism spectrum disorder. Further studies are needed to interpret how these many risk factors are related to each other and to an autism spectrum dissected diagnosis. This includes how genes interact with these risk factors, and whether some of the risk factors act together to modify risk.”

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By Denise Mann
HealthDay Reporter