05 Feb Male:Female Ratio of Autism May Be More Equal Than Recognized
MedicalResearch.com Interview with:
Dr. Fyfe
Dr. Caroline Fyfe PhD
Postdoctoral Research Associate
Life Long Health and Wellbeing Theme
University of Edinburgh
MedicalResearch.com: What is the background for this study?
Response: Autism (ASD) has traditionally been seen as a condition that disproportionately affects males. This study quantifies the sex bias across birth cohorts, ages, and calendar time, using the Swedish national population registers to follow ~ 2.7 million individual born between 1985 and 2020 throughout their lives. Among children under ten years old the male-to-female diagnosis ratio remained relatively stable at about 3:1.
In contrast, a rapid increase in diagnoses of ASD among females during adolescence, produced a “female catch-up effect” that resulted in near parity of ASD prevalence between males and females by adulthood.
MedicalResearch.com: What are the main findings?
Response: These patterns may reflect, at least in part, evolving diagnostic practices and increasing public awareness of ASD in females, although the registers themselves do not contain direct measures of those factors.
MedicalResearch.com: What should readers take away from your report?
Response: That the life-long male to female ratio for autism may be significantly lower than previously thought and may, in fact be due to later diagnosis of females with ASD, rather than there being an actual sex difference.
MedicalResearch.com: What recommendations do you have for future research as a results of this study?
Response: Future research should look more closely at why females are diagnosed with ASD later than males, and whether there are missed opportunities for earlier diagnosis of females.
MedicalResearch.com: Is there anything else you would like to add? Any disclosures?
Response: The study is part of a larger collaboration looking at sex differences in autism, that includes the examination of genetic and environmental risk factors. It is funded by the Simons Foundation, New York.
Citation:Time trends in the male to female ratio for autism incidence: population based, prospectively collected, birth cohort study doi:10.1136/bmj-2025-084164
https://www.bmj.com/content/392/bmj-2025-084164
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Last Updated on February 5, 2026 by Marie Benz MD FAAD
