Children born to mothers who had the flu during pregnancy or fevers lasting more than a week may have a slightly higher risk for autism, new research suggests.

"Our findings are interesting for research purposes, but they should not alarm women who are pregnant," says researcher Hjordis Osk Atladottir, MD, PhD, of Denmark's University of Aarhus. "It needs to be emphasized that around 98% of the women in this study who experienced influenza or fever or took antibiotics during pregnancy did not have children with autism."

The study, published today in the journal Pediatrics, included 97,000 children born in Denmark between 1997 and 2002, including those with a diagnosis of autism spectrum disorder.

There was no evidence of an increase in autism risk among children born to women who had colds, sinus infections, and urinary and genital tract infections during pregnancy. But having the flu during pregnancy was linked to a twofold increase in a woman's chance of having a child diagnosed with an autism spectrum disorder before the age of 3.

Children whose mothers reported having a fever lasting for more than a week had a threefold increase in autism risk. Still, despite these increases, the overall risk remained low.

Read more from WebMD.