Studies have suggested that the firstborn child of parents that are older (more than 35 -40 years of age) is at an increased risk of ASD than younger parents (25-30 years). Maureen Durkin, an epidemiologist conducted a prospective population-based cohort study to determine whether advanced parental ages were risk factors for development of ASD. The study group was comprised of 1251 children aged 8 years with a confirmed diagnosis of ASD. The findings suggested a 3-fold increase in the risk in ASD for child born to older parents compared to the younger age group.