A new study finds a link between illness during pregnancy and autism, but experts are already urging caution when interpreting the results. Danish researchers found that expecting mothers who suffered from the flu were twice as likely to have a child who developed an autism spectrum disorder, while those who had a fever that lasted more than a week were three times more likely. Pregnant women who reported other illnesses, such as a cold or sinus infection, were not found to be at higher risk.
"The study is really exploratory, and more research needs to be done," warns a CDC director. US health officials also note that the study doesn't offer a specific cause of autism in the noted cases, USA Today reports. But another autism researcher calls the results "noteworthy." She co-authored a previous study finding similar results: Fever while pregnant more than doubled the risk of developmental delay, including autism, in children—but only if mothers did not take any medication to reduce the fever.