Introduction: Autism spectrum disorders (ASD) are a group of biologically based neurodevelopmental disorders characterized by impairments in three major domains: socialization, communication, and behavior. Although autism may be present in children with tuberous sclerosis complex or Fragile X, most of the cases are not related to a known genetic disorder. The prevalence of ASD has increased since the 1970s. Could this increase be related to a non-genetic factor?

Methods: To explore the association of some perinatal factors we devised a retrospective case control study.

Results: Interview of mothers are still ongoing. Tuberous sclerosis, Rett or Fragil X cases were excluded. Up to now we have information of 52 children aged 2 to 22 years and most of the autism cases are males (84%). A greater proportion of cesarean section (4:1) is found in the autism group than in the control (1.5:1). Ten percent of children in the autism group have not been breastfed at all (none in the control), and a greater proportion than in the control group is breastfed for less then 6 months.