Gender Ratios in Autism, Asperger Syndrome and Autism Spectrum Disorder

Skewed sex ratios indicative of a greater preponderance of males over females (approximating 4:1) has perhaps been the most constant collective finding in autism spectrum conditions. More recent investigations have indicated a potential change to traditional estimates of gender ratios. We undertook analysis to calculate contemporaneous gender ratios based on collective and individual sub-diagnoses. A sample of 1963 children diagnosed with autism (n = 460), Asperger syndrome (n = 366) or autism spectrum disorder (ASD) (n = 1137) were included for study. The overall gender ratio based on a year of birth between 1986–2007 was 7.38:1. Differences were found amongst the sub-diagnoses for the same period (autism = 6.54:1, Asperger syndrome = 12.07:1; ASD = 6.84:1). Analysis of annual trends indicated an irregular upwards tendency to gender ratios indicative of increasing over-representation of males with an autism spectrum condition despite no indication of greater disparity in population sex ratios at birth. Further independent studies are required to corroborate our findings.