Autism in Girls: Why It Is Often Recognized Later, and What Research Shows

How common is autism in girls?

In CDC's Autism and Developmental Disabilities Monitoring (ADDM) Network data for 2022, autism was identified in 49.2 per 1,000 8-year-old boys (about 1 in 20) and 14.3 per 1,000 girls (about 1 in 70), a ratio of 3.4 to 1. The ratio has fallen in recent reports, from 4.2 in 2018 to 3.8 in 2020 and 3.4 in 2022. But CDC notes that the difference in prevalence between boys and girls actually widened over that time, so the falling ratio "could be deceiving" if read as better identification of girls. [1]

These data come from 16 U.S. communities that are not nationally representative, and sex was taken from records rather than how families identify. [1]

Are girls really less likely to be autistic, or just less likely to be diagnosed?

Probably some of both.

Evidence that girls are being missed. Loomes and colleagues pooled 54 prevalence studies covering more than 13 million people, including 53,712 autistic people. Overall, the male-to-female ratio was about 4.2 to 1. But in studies that screened the general population to find autistic people whether or not they had a diagnosis, the ratio was about 3.3 to 1, compared with about 4.6 to 1 in studies that only counted children who had already been diagnosed. The authors concluded that the true ratio among children who meet criteria is closer to 3 to 1 and that there appears to be a diagnostic gender bias. [2]

These numbers come from different methods and are not directly comparable, but the pattern is consistent: more boys than girls, with a smaller gap when researchers go looking rather than counting existing diagnoses. [1] [2] [8]

Evidence that a real difference remains. In the Baby Siblings Research Consortium, 1,241 younger siblings of autistic children were followed from infancy at 15 sites. Even with this close follow-up, 26.7% of boys and 10.3% of girls were autistic by age 3. [8] Researchers have proposed biological explanations, including a "female protective effect," but reviews describe the evidence for these as mixed. [5] [8]

Why does this matter? Because a girl who has autistic traits should not be dismissed because "girls aren't usually autistic." Autism is less common in girls, but it is not rare.

Why might autism be recognized later in girls?

Several explanations have research support, though none is proven to explain the gap on its own.

• Less obvious or disruptive signs. AAP notes it has been suggested that girls may have less intense symptoms and fewer externalizing (outwardly disruptive) behaviors, and that these differences may partly explain underdiagnosis. [3] The evidence is not uniform: a 2025 meta-analysis found autistic girls scored slightly higher than boys on one parent-report measure of externalizing problems. [6]
• Different interpretation by adults. Lai and colleagues describe a possible gender-based interpretation bias from families, schools, doctors, or diagnosticians, such as reading social difficulties in a girl as "just being shy." [4]
• Other diagnoses come first. Anxiety, depression, or another condition may be identified and treated while underlying autism goes unrecognized, sometimes called diagnostic overshadowing. [4] [5]
• Criteria and tools shaped by boys. Hull and colleagues note that diagnostic criteria and tools were developed largely from male samples, and cite studies finding that girls need more additional difficulties than boys to receive a diagnosis despite similar levels of autistic traits. [5]
• Strong language or school skills. AAP notes that children with milder signs or average or above-average intelligence may not be identified until school age, when social demands increase. [3]

Is diagnosis actually later for girls? The evidence is mixed. A meta-analysis of studies published from 2012 to 2019 found that studies examining factors like gender often reported conflicting or inconclusive results on age at diagnosis. [10] In an Ontario study of 365 autistic children (20% girls), parents of girls and boys first became concerned at similar ages, before age 2 on average, but girls were diagnosed later (on average, diagnosis came after age 5 for the whole group), and higher verbal ability was linked to later diagnosis more strongly in girls than in boys. [9] Hull and colleagues' review cites several studies finding later diagnosis in girls. [5]

What can autism look like in some girls?

This is not a checklist. Every autistic child is different, and the core features of autism are the same for girls and boys: differences in social communication and interaction, and restricted or repetitive behaviors, interests, or sensory responses. [3] [5] Researchers describe some patterns that, on average, may make autism harder to see in some girls: [5] [6]

• Wanting friends, and finding them hard to keep. Hull and colleagues' review describes studies finding that autistic girls tend to have higher social motivation than autistic boys, but may find it harder to keep friendships or manage conflict with peers. Compared with other girls, rather than with autistic boys, their social differences may be clearer. [5]
• Interests that do not look unusual. Some studies suggest that autistic girls' intense interests more often involve topics such as animals, fictional characters, or psychology, and may be underestimated if evaluators do not ask about them. [5]
• More visible difficulties at home than in an assessment. In a 2025 meta-analysis of 67 studies, autistic girls scored as less severe than boys on the ADOS, a standardized clinical observation, but scored as having more social difficulties on parent- and teacher-report questionnaires such as the SRS-2. The differences were small. [6]
• Anxiety and low mood. Most research summarized by Hull and colleagues finds that autistic girls and women are more likely than autistic boys and men to have co-occurring anxiety or depression, although some studies of younger children find no difference. [5]

Repetitive behaviors do not always differ by sex. The 2025 meta-analysis found no significant difference between autistic girls and boys in repetitive behaviors on the two measures it pooled. [6] If repetitive movements are part of the picture, a separate guide on stimming explains what research says about them.

What is masking or camouflaging?

Camouflaging describes conscious or unconscious strategies that make autistic characteristics less visible in social situations, such as copying other people's facial expressions, forcing eye contact, or holding back from talking about a favorite interest. [5]

• In children: Wood-Downie and colleagues studied 84 children aged 8 to 14 in U.K. mainstream schools. Girls with an autism diagnosis or high autistic traits showed social reciprocity similar to non-autistic girls, while autistic boys showed less reciprocity than non-autistic boys, despite similar levels of autistic traits in autistic girls and boys. The authors interpreted this as evidence of more camouflaging in autistic girls, which may delay recognition. [7]
• In adolescents and adults: a meta-analysis of 10 studies using a self-report camouflaging questionnaire found that autistic females scored higher than males, a small difference on average. [6]

What researchers do not yet know. A 2026 critical review of 389 studies found that researchers use terms such as masking, camouflaging, and compensation inconsistently, and that the most widely used questionnaire has mixed evidence of validity and may partly measure other things, such as social anxiety. It also found that camouflaging research overrepresents women diagnosed in adulthood and underrepresents autistic people with intellectual or language disabilities or higher support needs. [11] Camouflaging is often linked to mental health difficulties, but a study that followed 332 autistic adults for about two years did not find strong evidence that camouflaging leads to worse mental health, and the direction of the link remains unclear. [12]

Do early signs look different in toddler girls?

For toddlers, the evidence points to more similarity than difference. In the Baby Siblings Research Consortium study of 1,824 infants, boys on average had more repetitive behavior and lower developmental scores than girls, but these differences were seen whether or not children were autistic. The authors concluded that sex differences in young autistic children appear to reflect typical sex differences rather than something specific to autism. [8]

That means the early signs in our guide Early Signs of Autism in Toddlers apply to girls, too: differences in responding to name, gestures, sharing attention, and back-and-forth interaction, alongside repetitive behaviors or sensory differences. AAP notes that some children with milder signs are not identified until school age, when social demands increase. [3]

What the research cannot tell us

• How any one girl will present. All of these findings are averages across groups, with lots of overlap between girls and boys. [6]
• Cause and effect. Most studies are observational. They show patterns, such as later diagnosis or more anxiety in some groups, but not what causes them. [9] [12]
• Gender diversity. Most research compares boys and girls by recorded sex and uses a binary approach to gender. Hull and colleagues note this leaves out the substantial minority of autistic people with non-binary or fluid gender identities. [5]
• Girls with intellectual disability or higher support needs. Many studies of sex differences and camouflaging excluded or underrepresented these girls. [6] [11] In CDC's data, a similar share of autistic girls and boys had intellectual disability (40.4% and 39.5%). [1]
• Whether results apply everywhere. Many studies summarized here were done in the U.S., Canada, the U.K., and elsewhere in Europe, and diagnostic practices vary widely, even between U.S. communities. [1] [7] [9] [12]

What you can do now

1. Trust specific observations. Note concrete examples: how your daughter plays and talks with other children, what happens at transitions, what her interests are and how intensely she pursues them, how she seems after school, and any sensory differences (our guide Sensory Differences in Autistic Children covers that research). Specific examples are more useful than trying to match a "female autism" profile. This is a practical suggestion, not a test.
2. Raise concerns at any age. CDC says screening should happen whenever you or your doctor have a concern, not only at scheduled visits. [13] Ask your daughter's healthcare provider about a developmental or autism evaluation if concerns continue.
3. Do not wait for a diagnosis to get support. In the U.S., if your child is under 3, you can contact early intervention directly; if she is 3 or older, you can ask your public school district for an evaluation. See How to Get Early Intervention Services.
4. Ask about the evaluator's experience. It is reasonable to ask whether an evaluator has experience assessing girls and children with strong language skills, and how they gather information from home and school as well as the clinic.
5. Take emotional health seriously. If your daughter shows signs of anxiety or low mood, mention them, and ask whether autism has been considered alongside them. [4] [5]
6. Know when to act quickly. If your child loses words, skills, or social engagement she used to have, contact her healthcare provider promptly. AAP says medical evaluation of loss of milestones is indicated. [3] If she talks about harming herself, seek urgent help right away.

Frequently asked questions

The bottom line

Autism is more common in boys, but research suggests many autistic girls are recognized late or missed, partly because their differences can be quieter, can be masked, or can be interpreted as shyness or anxiety. The differences are averages, the research has important gaps, and none of the sources we reviewed describes a separate validated autism test or checklist for girls. If something about your daughter's development concerns you, you can ask for screening and an evaluation at any age, start support without waiting for a diagnosis, and look for evaluators who will consider the whole picture. [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13]