Why 80% of autistic girls aren't diagnosed until adulthood
With waiting lists for autism assessments soaring, girls are more likely than boys to be undiagnosed until adulthood, leading to lasting effects on their education and mental health.
80% of autistic girls remain undiagnosed at age 18 — diagnosis rates only level out between males and females by age 20.
The median diagnosis age for girls is 15.9 years, compared to 13.1 years for boys.
More than 170,000 people in England are waiting for an autism diagnosis; 59% are under 18.
Masking — suppressing natural autistic traits to appear "neurotypical" — is a major reason girls go unrecognised, and it's linked to anxiety, depression and burnout.
More than 13,000 autistic pupils missed 50% or more of the 2024/25 school year.
Cubbie offers a judgement-free space to regulate, without the need to mask.
Latest figures reveal 80% of autistic girls remain undiagnosed at age 18, with diagnosis rates levelling out between males and females by the time they’re 20. This massive surge in late diagnoses challenges previous assumptions that autism is more common among males. Autistic children are also likely to miss huge chunks of schooling due to mental health issues.
The scale of the problem
1 in 100 people in the UK are autistic.
The median age for autism diagnosis in girls is 15.9 years. For boys, it's 13.1 years.
Various studies suggest that the ratio of autistic males to females ranges from 2:1 to 16:1. The most-up-to-date estimate is 3:1.
More than 170,000 people in England are waiting for an autism diagnosis; 59% of whom are under 18 (National Autistic Society).
Why is autism so often missed in females?
Research and diagnostic criteria have traditionally focused on behaviours more commonly seen in boys, meaning girls' experiences often didn't fit traditional stereotypes.
Clinical neuropsychologist Dr Susan Epstein explains: "The model that we have for a classic autism diagnosis has really turned out to be a male model. Girls tend to have a quieter presentation, with not necessarily as much of the repetitive and restricted behaviour, or it shows up in a different way."
Why autism assessment criteria are ‘male-centric’
Cathy Wassall, CEO of the Autistic Girls Network, agrees. She points out that the interests often used as red flags — such as trains — are stereotypically male, so a girl's intense focus on drawing or reading may never be flagged as a "special interest," simply because those hobbies look ordinary. Wassall also notes that the effort autistic girls put into observing and copying non-autistic peers, in order to blend in socially, can itself become an all-consuming preoccupation.
"Autistic girls, much like other autistic people, may engage in different repetitive behaviours," she explained. "This may not look like lining up objects or repeating words out loud, although it could. It may instead look like re-reading the same book or re-watching the same film over and over again because it provides a sense of comfort and predictability. It may involve re-doing homework until it’s ’perfect’ or repeating a certain behaviour which is comforting to them."
Underlying all of this is the issue of masking: girls are statistically more prone than boys to concealing their natural behaviours, which makes accurate diagnosis even harder.
What is masking in autism?
Masking is when someone hides or suppresses their natural behaviours to appear "neurotypical" and avoid judgement, misunderstanding, or negative consequences. It often involves:
Suppressing stimming (like rocking, hand-flapping, tapping, chewing clothing or humming) to avoid looking "different"
Forcing eye contact even when it feels painful or distracting
Copying speech patterns or body language to blend in socially
On the outside, the individual may seem calm and engaged. Yet on the inside, they are likely to be overwhelmed, anxious, or exhausted.
The government has been strongly critical of professionals who teach children masking strategies to help them "cope" with their neurodivergence. Its study into identifying and supporting the needs of children with SEND in mainstream settings, cited masking as harmful, noting that interventions "that focus narrowly on observable behaviour or social communication may encourage masking or suppression, particularly among autistic pupils," and that "masking can also lead to poor mental health outcomes for autistic individuals."
Why masking gets overlooked during assessment
Girls with average or above-average intellectual functioning are more likely to mask, as they often develop more effective strategies to mask or internalise traits, making them less noticeable during assessment.
Girls have been found to use more social language during assessments, leading assessors to perceive their social communication skills as stronger. This can create an appearance of social confidence that masks significant emotional distress, sensory overwhelm and, over time, burnout.
The effect of masking on mental health
Dr Epstein says undiagnosed autistic girls end up wondering what's wrong with them, which can lead to depression, anxiety and loss of self-esteem. The effort involved in trying to fit in often leads to exhaustion.
"That's the thing about imitating," she says. "You don't necessarily 'get' it so you're just trying to do what people do. If you're just trying to mimic and you don't really understand, it makes it pretty rough."
The pressure to mask can have significant consequences on mental health, including:
Increased anxiety: the constant need to conform can lead to heightened anxiety levels
Burnout: prolonged masking can result in emotional and physical exhaustion
Identity confusion: people may struggle to understand their true selves when they are always masking
A study into the effects of masking on mental health among 342 autistic adults found higher levels of masking in an attempt to avoid detection are linked to higher reports of past trauma — specifically, having been teased and shamed for autistic traits. The research also found masking was associated with greater anxiety, more depression symptoms, lower self-esteem, authenticity challenges, and burnout, and it calls into question the teaching of masking strategies in parenting, education, and therapy programmes for autistic people.
The knock-on effect on schooling
Anxiety can be a major part of an autistic girl's everyday life, especially when she is masking and trying her best to fit in. This may mean she holds it together all day at school, then releases her feelings through meltdowns, shutdowns or anxiety attacks once she gets home. This build-up of anxiety can lead to anxiety-based school avoidance, and it can also cause situational mutism.
In a girl not yet recognised as autistic, persistent absence from school and situational mutism might be written off as "behavioural issues." However, they may be signs of undiagnosed autism. This leads to the alarming statistic that thousands of autistic pupils are missing the equivalent of 4.5 months or more of the school year.
More than 13,000 autistic pupils missed 50% or more of the 2024/25 school year, according to Department for Education statistics. Autism charity Ambitious About Autism cites mental health issues as the biggest cause of non-attendance among autistic pupils, at 62%.
A call for change
Dr Judith Brown, head of evidence and research at the National Autistic Society, says: "Gender should never be a barrier to receiving an autism diagnosis and access to the right support. Historically, it was wrongly assumed that autistic people were mostly men and boys, but we now know that women and girls are more likely to 'mask' what [are] traditionally thought of as signs of autism, making it harder to identify the challenges they face."
The charity launched an awareness initiative to highlight late diagnoses of autism in women.
But awareness alone doesn't help a girl get through the school day while she waits, sometimes for years, for a diagnosis. Schools need something they can offer now.
Cubbie: a safe space to regulate, without the need to mask
This is the gap Cubbie is designed to close. If masking is the effort of holding it together to look "fine" on the outside while overwhelmed on the inside, then what autistic girls need isn't another environment to perform in — it's a genuine space where regulation doesn't require a performance.
Cubbie is a personalised sensory regulation solution that offers a safe and familiar space where individuals can go to reset, feel calm, and regulate — where they can be themselves without the need to mask. Designed as a blank canvas, Cubbie offers personalised, occupational therapy-designed sensory regulation support, providing a unique experience tailored to individual needs.
Why this matters specifically for undiagnosed and masking girls
Because so many autistic girls are still undiagnosed, school-based support often can't wait for a formal label. Cubbie doesn't require one. It gives any pupil — diagnosed or not, recognised or not — somewhere to release the sensory and emotional load that's been suppressed all day, before it turns into the shutdowns, meltdowns or school avoidance so many families see once they get home.
For girls whose stimming, sensory overwhelm or anxiety have gone unnoticed precisely because they've learned to hide them well, Cubbie offers something rare: a space where there's nothing to hide, and nothing to prove.
Supporting schools to catch what assessments often miss
Cubbie is one practical step towards a vision of creating environments where individuals don't have to change themselves to fit in — the environment flexes to support them. It also gives staff a consistent, evidence-informed way to notice regulation needs that traditional, male-centric assessment models can overlook, building a picture of a pupil's needs over time rather than relying on a single point-in-time diagnosis.
Masking can make social situations smoother for the people around them, but it comes at a cost for the autistic person, making their own life more exhausting. True inclusion means recognising that no one should have to hide to be accepted.
For more information on how Cubbie can support the girls in your school who are struggling silently, get in touch.
