The recent surge in autism diagnoses is not spread evenly across the population.
A new analysis of nearly a decade of US health records shows the sharp increase since 2020 is being driven almost entirely by girls and women.
Those same females are still being identified an average of 3.4 years later than males.
The average age at first diagnosis was 15.7 years for females and 12.3 years for males.
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The study, published in JAMA Network Open in July 2026, tracked first-recorded autism spectrum disorder diagnoses in 171,134 patients across a large Midwestern health system from 2016 to 2024.
Male diagnosis rates stayed flat or fell across every age group. Female rates rose steeply after 2020, with a 19% annual increase overall.
What the numbers actually show
Among adolescent girls, incidence climbed at an annual rate of 22.3% between 2020 and 2024.
Among younger girls, the annual rise since 2020 was 17.4%.
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Among boys, diagnosis rates remained stable or declined across all age groups.
The authors argue this is not an epidemic of new autism.
The post-pandemic increase in diagnoses reflects increased recognition of females with autism spectrum disorder rather than a uniform population-level increase, the study concludes.
"Late diagnosis means years of missed support, accommodations, and self-understanding during crucial developmental transitions," said Erick Messias, chair of the Department of Psychiatry and Behavioral Neuroscience at Saint Louis University School of Medicine and the study's lead author.
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Why girls slip through screening
Autism screening was built around how boys present.
Girls often show a quieter picture, with fewer of the obvious repetitive behaviors and narrow interests that flag boys for evaluation.
"The model that we have for a classic autism diagnosis has really turned out to be a male model," clinical neuropsychologist Susan F. Epstein told the Child Mind Institute.
Many autistic girls also become skilled observers of social behavior and learn to mask what feels different.
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Autism Speaks describes that as forcing eye contact, holding back self-soothing behaviors, imitating other people's expressions and building scripts for conversations.
That quieter picture is often mistaken for something else. Child psychiatrist Wendy Nash said to Child Mind Institute she sees "a lot of girls who are diagnosed with ADHD when they're young who actually meet the criteria for autism."
Depression, anxiety and low self-esteem are also common labels along the way. Long-term masking can itself feed anxiety, depression and stress.
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This article is made and published by Ida-Marie Palm Varbæk, who may have used AI in the preparation.