Recent research from the UK shows there may be far higher numbers of undiagnosed autistic women and girls than previously thought, and that females masking autistic traits is a contributing factor.
A medical doctor diagnosing privately in New Zealand says, in our public system, many women fall through the cracks.
Joanne Dacombe is an autistic woman from the Kāpiti Coast who was not diagnosed with the condition until she was 48.
"I was diagnosed later in life after a mental health issue which, in hindsight, I believe was triggered by autistic burnout causing major depression," she says.
Autistic burnout is an accumulation of years of trying to appear normal and cope as a neurotypical, Ms Dacombe says.
"The strain and drain of it suddenly becomes too much and an autistic person falls apart."
Shouldering the cost required to privately pursue that diagnosis was validating, Ms Dacombe says.
"I decided to pursue formal diagnosis to rule out other conditions and because I really wanted to know if I truly was autistic," she says.
"I think formal diagnosis has allowed me greater freedom and validity to advocate for autistics. It has enabled me to be confident about who I am, and why I experience the world as I do."
Increasingly, the private route is where women turn to receive autism diagnoses in New Zealand.
Dr Ava Ruth Baker, a medical doctor with post-graduate qualifications in mental health and autism, has provided a private service for autism spectrum disorder (ASD) diagnosis and support for all ages for the past 20 years.
She says, in the past 6 months, she has diagnosed more females than males - a ratio of five females to every three males.
"Most of these either had requests for ASD assessment within the public sector declined, or had been told their problems were due to anxiety or parenting issues."
Dr Baker continues: "One had been told by a specialist that 'it can't be autism because girls don't get autism' and another that the girl was 'too complex' to assess.
Others had had their concerns about ASD dismissed through overly simplistic appraisals of social skills."
Ann Marie Pike, a Paraparaumu-based child and family therapist specialising in ASD/ADHD, learning and behaviour, says autistic girls often fall under the radar if they are not screened for ASD when they present with mental health conditions.
"I find that girls on the spectrum most often first present to clinicians in mental health with secondary co-morbid issues of anxiety, depression, eating disorders or obsessive compulsive concerns. If diagnostic professionals don't also screen for ASD at that time, girls are more versed in social cues than their male counterparts of the same age, and will go under the radar for a further diagnosis of ASD."
Ms Pike notes the diagnostic checklist for males doesn't cover the ASD traits of females well.
"For example, females may have better eye contact and be able to carry conversation easier. They may dress well and have better self care - all because, as females, they spend more time observing others than their male counterparts.
"They may copy others' behaviours, speak with an accent they've picked up from watching television and be highly skilled in art or music from a young age. All of which are not considered when screening for ASD necessarily."
Autism New Zealand's website states a ratio of one woman to every nine men has Asperger syndrome. But the organisation's chief executive Dane Dougan believes the official figures are misleading.
"It is now generally accepted that females are better at masking the signs of autism and so are not being diagnosed as readily as males are. Diagnostic tools have been developed more for males than females," Mr Dougan says.
"In some areas there are massive waiting lists. Autism NZ is carrying out research to investigate standardising diagnostic processes across the country, and looking at gender bias as part of that as well," he says.
The disparity is also receiving attention in international research.
The Guardian reports that "Recent research, based on active screening rather than clinical or school records, found a ratio of 3:1 [males to females with Asperger syndrome]."
Professor Francesca Happé, director of the Social, Genetic & Developmental Psychiatry Centre at King's College London, told the Guardian: "We've overlooked autism in women and girls by viewing it as a 'male condition'.
"I think there's a real gender equality issue here," she said.