The male-to-female ratio of autism spectrum disorder (ASD) may be more equal than commonly believed, according to an analysis of Swedish registry data published in BMJ. Observed discrepancies in ASD prevalence arise because females are more frequently diagnosed later in life.Why It’s Relevant
Early identification and intervention of ASD has been linked to better developmental outcomes in affected children. A perception that ASD is predominantly seen in males may bias screening practices and reduce timely identification of this disorder in females.
By the Numbers
- Researchers analyzed nearly 2.8 million individuals born in Sweden between 1985 and 2020—identifying 78,522 (2.8%) who were diagnosed with ASD by the end of 2022.
- Across the whole cohort, the male-to-female ratio of ASD was 1.6:1—though the data showed that the yearly gap has been shrinking over time.
- The average age of ASD diagnosis was 14 years—among males, diagnoses peaked between ages 10 to 14 while in females diagnoses peaked between ages 15 to 19.
- In 2022, the ASD male-to-female ratio at age 10 was 3:1—but by age 20, the ratio dropped to 1.2:1
The Other Side
The study only considered ASD diagnosis and not factors such as disorder severity or which ASD traits were present in males versus females, which would provide additional clinical perspective. The study also didn’t examine the prevalence of conditions that frequently co-occur with ASD, such as intellectual disability or attention deficit/hyperactivity disorder.
What’s Next
This study’s findings show a pattern of significant “catch-up” in recognizing ASD in females over the past 40 years in Sweden. Now, the researchers said there is a need to investigate why females still receive diagnoses of ASD at a later age on average than males.
Related Information
Source
Caroline Fyfe, et al. Time trends in the male to female ratio for autism incidence: population based, prospectively collected, birth cohort study. BMJ. Published February 4, 2026. doi: 10.1136/bmj-2025-08416
(Image: Getty Images/iStock/Lacheev)
