Why Are Girls Diagnosed with Autism Later in Ontario?
Direct answer
Research shows girls are often diagnosed with autism later than boys (Lockwood Estrin et al., 2021). This delay occurs because diagnostic tools were developed primarily from male presentations, some girls "mask" or camouflage social difficulties, and clinicians may not recognize autism in girls who do not display stereotypical behaviours. In Ontario, speaking up early for an assessment can matter.
Why Timing Matters
The wait outlasts the window.
Clinical research (American Academy of Pediatrics; Hyman et al., Pediatrics 2020) identifies birth to age six as the peak neuroplasticity window for autism intervention. Ontario's reported minimum wait is 5+ years for families registered in August 2021 (community-reported, Ontario Autism Coalition, July 2026).
Example: an illustrative child's journey through the Ontario Autism Program
Registered at age 3. Services begin at age 8, after 5+ years for families registered in August 2021 (community-reported, Ontario Autism Coalition, July 2026), most of it inside the intervention window.
| Measure | Age range |
|---|---|
| Early-intervention window (AAP) | Birth to age 6 |
| Example wait using the OAC-reported minimum (registered age 3) | Age 3 to age 8 (5 years) |
| Age when services begin in this example | Past age 6 |
✓ Intervention before 6
Research shows 2× greater gains in cognitive and adaptive functioning. Some children lose their diagnosis entirely. The brain's plasticity makes early therapy dramatically more effective.
◌ Intervention after 6
Reduced neuroplasticity means slower progress, higher lifetime costs, and poorer outcomes. Every year of delay narrows the range of achievable milestones. Ontario's waitlist guarantees this for most families.
Of the 71,263 children on the unfunded backlog, the majority were registered between ages 2 and 4. At the current pace, most will age past 6 before receiving any core funding , missing the window that the American Academy of Pediatrics and every major autism research body identifies as critical.
SourceAmerican Academy of Pediatrics (Hyman et al., Pediatrics 2020) · Ontario MCCSS OAP data via FOI · Wait: 5+ years for families registered in August 2021 (community-reported, Ontario Autism Coalition, July 2026).
About This Article
Published:
Last updated:
Why the Diagnostic Gap Exists
- Three factors drive the later diagnosis of autism in girls: (1) Masking/camouflaging — girls are more likely to mimic social behaviours from peers, hiding their difficulties in structured settings like school. (2) Diagnostic bias — much of the research used mostly male samples, and common assessment tools were designed around how autism looks in boys. (3) Clinical expectations — many clinicians still associate autism with the "classic" male presentation (lining up toys, train obsessions) and may not recognize female-typical presentations (such as a strong wish to interact with others, or copying peers).
- The result is that many girls are first given other diagnoses before autism is eventually identified.
Frequently asked questions
Girls are often diagnosed later due to masking behaviours, diagnostic tools designed around male presentations, and clinical expectations biased toward male presentations.
Request a referral from your family doctor or pediatrician to a psychologist or developmental pediatrician experienced with autism in girls. Ask whether the clinician has experience assessing girls. Provide examples of difficulties at home (masking may hide difficulties at school).
Yes. Level 1 autism can be missed when masking makes social difficulties less visible. The effort of masking can cause exhaustion and anxiety, and autistic adults link it to burnout. Girls with Level 1 autism can still need support.
Write down the behaviours you notice and how they affect daily life. Ask your clinician to consider autism even if earlier screening did not raise a concern.
Sources
Lockwood Estrin et al. (2021), "Barriers to autism spectrum disorder diagnosis for young women and girls: a systematic review," Review Journal of Autism and Developmental Disorders, 8, 454-470
Checked
Loomes et al. (2017), "What is the male-to-female ratio in autism spectrum disorder?" Journal of the American Academy of Child & Adolescent Psychiatry
Checked
Public Health Agency of Canada — Autism spectrum disorder: Canadian Health Survey on Children and Youth, 2019
Checked
Next step near you
Where to be assessed near you
- TorontoHolland Bloorview
- OttawaCHEO
- MississaugaErinoakKids (Mississauga Facility)
- BramptonErinoakKids (Brampton)
- North YorkHolland Bloorview (referral)
- ScarboroughSickKids (referral)
See every Ontario city we track
Assessment routes, local providers and school boards are tracked city by city. Pick the one closest to you.
Where the wait clock starts
A child's place in the Ontario Autism Program queue is set by the AccessOAP registration date. 71,263 children are registered and still waiting for core funding (MCCSS FOI via OAC · May 2026).
Next steps
Keep going with related guidance, tools, and evidence.
Related questions
What Does an Autism Assessment Include in Ontario?
A comprehensive autism assessment includes developmental history, clinical observation, often a standardized tool (ADOS-2, ADI-R), and other tests like cognitive testing when needed.
Autism Levels 1, 2, and 3: What Do They Mean?
Autism levels 1, 2, and 3 explained: what each DSM-5 support level means and how all three qualify for Ontario Autism Program funding.
Autism vs ADHD: Dual Diagnosis & Treatment in Ontario
Autism and ADHD often occur together. Learn about dual diagnosis for OAP funding, diagnostic differences, and medication in Ontario.
About this page
Check the author’s context, review method, and how to report an error.