An exploratory research study was conducted to examine whether infections during pregnancy has anything to doo with autism. Children whose mothers reports having flu or fever lasting more than one week or using antibiotics were at risk for autism. For example children whose mothers experienced flue during pregnancy were twice likely to have been diagnosed with ASD and those whose mothers experienced fever for more than a week were three times likely to have been diagnosed with ASD. However, the result of the study showed that less then 1% of children whose mothers reported any infection had autistic disorder.
I think this aspect of risk factor study is quite interesting.
Atladottir HO, Henriksen TB, Schendel DE, Parner ET. “Autism after Infection, Febrile Episodes, and Antibiotic Use during Pregnancy: an Exploratory Study.” Pediatrics 2012.