The epidemiology of autism is the study of factors affecting autism spectrum disorders (ASD). A 2012 review of global prevalence estimates of autism spectrum disorders found a median of 62 cases per 10,000 people. There is a lack of evidence from low- and middle-income countries though.
ASD averages a 4.3:1 male-to-female ratio. The number of children known to have autism has increased dramatically since the 1980s, at least partly due to changes in diagnostic practice; it is unclear whether prevalence has actually increased; and as-yet-unidentified environmental risk factors cannot be ruled out.
The risk of autism is associated with several prenatal factors, including advanced parental age and diabetes in the mother during pregnancy. ASD is associated with several genetic disorders and with epilepsy, and autism is associated with mental retardation.
Read more about Epidemiology Of Autism: Autism and Its Causes, Frequency, Genetics, Risk Factors, Comorbid Conditions