Autism in girls and women has been hiding in plain sight, new research suggests. Diagnoses among females are climbing fast, while those among males have stayed stable or fallen.

The increase may be driven by better recognition rather than a surge in new cases, researchers say. It also suggests the diagnosis gap between the sexes is smaller than long assumed.

A team at Saint Louis University reviewed the health records of 171,134 patients in a large Midwestern health system. The findings, covering 2016 to 2024, were published in JAMA Network Open.

Female Diagnoses Rose After 2020

New autism diagnoses in females rose by 19 per cent a year from 2020 through 2024. The annual total nearly doubled, from 284 in 2016 to 513 in 2024.

The rise was steepest among the young. Diagnoses in female children climbed by 17.4 per cent a year after 2020, and by 22.3 per cent among adolescent girls.

Diagnoses among boys and men stayed stable or fell over the same years. The pattern extended across every age group studied, although the rise of among adult women was not statistically significant.

The researchers said the commonly cited four-to-one male-to-female diagnosis ratio may overstate the difference. The true figure could be nearer three-to-one, or lower still.

A separate study of Swedish birth records points the same way. It found the male-to-female ratio falling as age at diagnosis rose, until it may no longer be detectable in adulthood.

Why Autism Is Missed in Women

Lead author Erick Messias is a professor of psychiatry at Saint Louis University School of Medicine. He said autism is marked by a pattern of traits, not one characteristic.

Women undiagnosed into adulthood often engage in 'significant social camouflaging or masking', Messias said. He called it a conscious effort to conform to social conventions that do not come naturally.

Masking can mean copying social cues, rehearsing conversations and closely regulating behaviour. Messias said that camouflaging can be highly mentally demanding.

Girls and women may also be more likely to keep friendships going or seek company. That can make autism less obvious when doctors look for a stereotypical presentation.

Difficulties in females are more likely to surface as internal distress than as disruptive behaviour, Messias said. That can leave the condition overlooked.

Some women are diagnosed with anxiety, depression or attention deficit hyperactivity disorder, known as ADHD, before autism. The study did not examine how far those overlaps delay recognition.

The Cost of Late Diagnosis

Females in the study were diagnosed an average of 3.4 years later than males. The average age at diagnosis was 15.7 years for females and 12.3 years for males.

That delay can be significant. Earlier diagnosis often helps children and families reach educational support, behavioural therapies and other services that can improve quality of life.

Masking gets harder to sustain as demands build. Work, relationships and parenting bring pressures that were easier to manage earlier in life.

Messias said autism in women and girls is often tied to other conditions. These include circulation problems, immune-related disorders and chronic fatigue.

Women diagnosed with those or related conditions 'may be good candidates for further screening for autism and ADHD', he said. The same delay has been seen in ADHD referrals.

The analysis covered a single health system, whose wider database contains records for more than five million patients across four states. It did not investigate the reasons behind the delay.

Family and friends 'don't have to see every past experience in exactly the same way' as a newly diagnosed woman, Messias said. But they can respect her perspective and give her space.

Frequently Asked Questions

  • Why is autism often missed in women?
    Autism in women is often missed because they may engage in social camouflaging or masking, making it less obvious when doctors look for a stereotypical presentation.
  • What is the impact of late autism diagnosis in females?
    Late diagnosis can delay access to educational support, behavioural therapies, and other services that improve quality of life.
  • How does the diagnosis rate of autism differ between males and females?
    Diagnoses among females are increasing, while those among males have stayed stable or fallen, suggesting the diagnosis gap is smaller than previously assumed.
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