Objective To review the evidence for the presence of prenatal and perinatal factors that
affect the risk of autism and autism spectrum disorders. Data Sources Relevant articles were
identified by searching MEDLINE, screening reference lists of original studies, and
searching major journals likely to publish epidemiological studies on the topic. Study
Selection For inclusion in this review, studies required (1) a well-defined sample of cases
drawn from population-based registers or cohorts;(2) standardized, prospectively collected …