In the new analysis, researchers studied 701 children with autism spectrum disorders or developmental delays and 421 normal controls. After adjusting for age and other health and socioeconomic variables, they found that women who reported having had a fever during pregnancy were more than twice as likely as those who did not to have a child with a developmental disorder.
Among women whose fever had been treated with drugs like Tylenol or Advil, the risk was indistinguishable from that of mothers who reported no fever.
"Fever is an acute inflammatory response," said the senior author, Irva Hertz-Picciotto, a professor of environmental epidemiology at the Mind Institute of the University of California, Davis. "So there is a suggestion that inflammation of some sort may play some role in autism causation. Untreated fever seems to be the place where the risk is."
Image: Sick pregnant woman, via Shutterstock.