Autistic girls much less likely to be diagnosed, study says

Females may be just as likely to be autistic as males but boys are up to four times more likely to be diagnosed in childhood, according to a large-scale study.

Research led by the Karolinska Institutet in Sweden scrutinised the diagnosis rates of autism for people born in Sweden between 1985 and 2020. Of the 2.7 million people tracked, 2.8% were diagnosed with autism between the ages of two and 37.

They found that by the age of 20, diagnosis rates of men and women were almost equal, challenging previous assumptions that autism is more common among males.

“Our findings suggest that the gender difference in autism prevalence is much lower than previously thought, due to women and girls being underdiagnosed or diagnosed late,” said the lead author, Dr Caroline Fyfe.

The research calculated that in childhood, boys were diagnosed on average nearly three years earlier than girls – the median age at diagnosis was 15.9 for girls, but 13.1 for boys. Overall, boys were three to four times more likely than girls to be diagnosed with autism under the age of 10, although girls were found to “catch up” by the time they were 20, owing to a rapid increase in autism diagnosis during adolescence.

“These observations highlight the need to investigate why female individuals receive diagnoses later than male individuals,” the authors conclude.

Patient and patient advocate Anne Cary, writing in a linked editorial, said the research supported arguments that it was “systemic biases in diagnosis, rather than a true gap in incidence” that were behind the discrepancy in diagnosis rates.

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Source: The Guardian, 4 February 2026