BMJ

Autism’s gender gap narrows with age, Swedish data show

February 9, 2026

In a population-based Swedish birth cohort of nearly 2.8 million individuals followed for up to 35 years, autism diagnoses rose steadily across childhood, with boys diagnosed more often early in life but girls showing a marked “catch-up” during adolescence. By around age 20, the cumulative male-to-female ratio approached parity (≈1:1), suggesting the sex gap in autism incidence narrows substantially with age.

Clinical takeaway: Findings point to age- and period-related shifts in diagnosis rather than stable biological differences, raising concern that girls and women may be underrecognized earlier in life.

Source:

Fyfe C, et al. (2026, February 4). BMJ. Time trends in the male to female ratio for autism incidence: population based, prospectively collected, birth cohort study. https://pubmed.ncbi.nlm.nih.gov/41638711/