Autism Diagnosis Timing Varies by Sex

Registry data from Sweden show how autism diagnosis timing differs by sex from childhood through adulthood.

By
Kathryn Wighton
February 6, 2026
3 min

Conexiant

Objective:

To analyze the timing of autism spectrum disorder (ASD) diagnoses in relation to sex using Swedish registry data, highlighting the implications of these differences.

Approach:

Key Findings:

ASD diagnoses are more common in boys during childhood, while girls are diagnosed later, often in adolescence or early adulthood.
By 2022, the male-to-female diagnosis ratio decreased significantly, approaching unity by age 20.
The median age at diagnosis was 14.3 years, with incidence rates peaking among males aged 10-14 and females aged 15-19.

Interpretation:

The findings suggest that the decreasing male-to-female ratio for ASD over time may indicate systemic biases in diagnostic practices rather than true differences in incidence.

Limitations:

Reliance on register-based diagnoses limits assessment of symptom severity and co-occurring conditions.
Changes in registry coverage over time, particularly the inclusion of outpatient diagnoses, may have influenced diagnosis timing.
Findings may not be generalizable to populations with diverse backgrounds, as analyses were restricted to patients with Swedish-born parents.

Conclusion:

The study highlights the need to reconsider the interpretation of sex differences in autism diagnoses, suggesting that systemic biases may contribute to later recognition in females and calling for further research in this area.