Diagnosis of autism in girls is catching up with boys in Scotland and Sweden. In a large US health system, though, girls and women were still diagnosed an average of 3.4 years later than boys and men.
Scotland’s autism diagnosis gap between boys and girls is closing. Among children under 10, the ratio of autism diagnoses fell from 5.5 boys for every girl in 2014 to 2.2 in 2025.
Researchers at Queen Margaret University in Edinburgh published the figures in November 2025. Their review of case notes for 408 people across 30 diagnostic teams found that delays persist. Across autism, ADHD and intellectual disability, females were still diagnosed about five years later than males on average.
Sweden shows a similar shift. A study of 2.7 million people born between 1985 and 2022 found boys were more likely to be diagnosed in childhood, while girls caught up in adolescence. By age 20, the ratio of males to females diagnosed was close to equal, BMJ Group reported in February 2026.
Three years’ difference in one US health system
Girls and women were diagnosed an average of 3.4 years later than boys and men in a study in JAMA Network Open, published on 22 July 2026. The average age at diagnosis was 15.7 for females and 12.3 for males.
Researchers at Saint Louis University analysed electronic health records for 171,134 people from 2016 to 2024. The patients were seen by SSM Health, which covers parts of Illinois, Missouri, Oklahoma and Wisconsin.
New diagnoses among females showed no significant change before 2020. From 2020 to 2024 they rose by 19% a year, and annual cases went from 284 in 2016 to 513 in 2024. Among males, new diagnoses fell by an average of 3.8% a year over the whole period. The rise in females appeared in children and adolescents, while the upward trend among adult women was not statistically significant.
Saint Louis University said the rise reflects increased awareness and diagnosis in females. The paper calls for screening that takes account of how autism can present differently by sex. The Swedish team made a similar call in The BMJ. “These observations highlight the need to investigate why female individuals receive diagnoses later than male individuals,” they wrote.
Limits of a single Midwestern system
Most patients in the study were White and non-Hispanic. Diagnoses were counted from billing codes, which were not checked against clinical notes. People had to be in continuous contact with the health system to be included, which may favour those with stable access to care.
The cohort was also 63.8% female, and adults in it were mostly women. The authors say this makes comparisons between adult men and women hard to interpret. They describe their results as trends in recorded diagnoses among people using health care, which differ from population-wide incidence.
About one in 127 people worldwide had autism in 2021, the World Health Organization estimates. It notes that autism is often not diagnosed until much later than the age at which its characteristics can first be seen.
Seeking an assessment later in life
Adults who think they may be autistic can ask for an assessment. In England, the NHS advises people to speak to a GP to find out how to get one locally. People can also be referred while getting help for another condition. Anyone who struggles to get a referral can ask to see another GP for a second opinion.
NHS assessment teams for adults may speak to someone who knew the person as a child and someone who knows them now, such as a partner or family member. Women preparing for an assessment can ask those people in advance whether they are willing to take part.
This article is for information only and does not replace advice from a qualified health professional.
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