Rates of autism in girls and boys may be more equal than previously thought

Study raises questions around why female individuals are diagnosed later than males

BMJ Group

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Autism has long been viewed as a condition that predominantly affects male individuals, but a study from Sweden published by The BMJ shows that autism may actually occur at comparable rates among male and female individuals.

 

The results show a clear female catch-up effect during adolescence, which the researchers say highlights the need to investigate why female individuals receive diagnoses later than male individuals.

 

The prevalence of autism spectrum disorder (ASD) has increased over the past three decades, with a high male-to-female diagnosis ratio of around 4:1.

 

The increase in prevalence is thought to be linked to factors including wider diagnostic criteria and societal changes (eg, parental age), whilst the high male to female ratio has been attributed to better social and communication skills among girls, making autism more difficult to spot. However so far no large study has examined these trends over the life course.

 

To address this, researchers used national registers to analyse diagnosis rates of autism for 2.7 million individuals born in Sweden between 1985 and 2022 who were tracked from birth to a maximum of 37 years of age.

 

During this follow-up period of more than 35 years, autism was diagnosed in 78,522 (2.8%) of individuals at an average age of 14.3 years.

 

Diagnosis rates increased with each five year age interval throughout childhood, peaking at 645.5 per 100,000 person years for male individuals at age 10-14 years and 602.6 for female individuals at age 15-19 years.

 

However, while male individuals were more likely to have a diagnosis of autism in childhood, female individuals caught up during adolescence, giving a male to female ratio approaching 1:1 by age 20 years.

 

This is an observational study and the authors acknowledge that they did not consider other conditions associated with autism, such as ADHD and intellectual disability. Nor were they able to control for shared genetic and environmental conditions like parental mental health.

 

However, they say the study size and duration enabled them to link data for a whole population and disentangle the effects of three different time scales: age, calendar period and birth cohort.

 

As such, they write: “These findings indicate that the male to female ratio for autism has decreased over time and with increasing age at diagnosis. This male to female ratio may therefore be substantially lower than previously thought, to the extent that, in Sweden, it may no longer be distinguishable by adulthood.”

 

“These observations highlight the need to investigate why female individuals receive diagnoses later than male individuals,” they conclude.

 

These findings align with recent research and seem to support the argument that current practices may be failing to recognise autism in many women until later in life, if at all, says Anne Cary, patient and patient advocate, in a linked editorial.

 

She notes that studies like this are essential to changing the assumption that autism is more prevalent in male individuals than in female individuals, but points out that as autistic female individuals await proper diagnosis, “they are likely to be (mis)diagnosed with psychiatric conditions, especially mood and personality disorders, and they are forced to self-advocate to be seen and treated appropriately: as autistic patients, just as autistic as their male counterparts.”

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Journal

The BMJ

DOI

10.1136/bmj-2025-084164 

Method of Research

Observational study

Subject of Research

People

Article Title

Time trends in the male to female ratio for autism incidence: population based, prospectively collected, birth cohort study

Article Publication Date

4-Feb-2026

COI Statement

s://www.icmje.org/disclosure-of-interest/ and declare: support from the Simons Foundation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.

 

Testing menstrual blood for HPV could be “robust alternative” to cervical screening

Could offer a practical way to expand access to screening, say researchers

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Testing menstrual blood for human papillomavirus (HPV) could be a “robust alternative or replacement” for current cervical cancer screening by a clinician, finds a study from China published by The BMJ today.

 

The researchers say using menstrual blood for HPV testing is convenient and non-invasive, allowing women to collect samples at home, and therefore could offer a practical pathway to expand access to screening.

 

Certain types of HPV infection can develop into cervical cancer and HPV testing is a key part of cervical screening. But not all women attend screening appointments for reasons including fear of pain, concerns about privacy and stigma, and lack of awareness.

 

Testing menstrual blood for HPV infection shows promise as a convenient, non-invasive alternative to screening, but evidence is limited.

 

To address this gap, researchers in China compared the diagnostic accuracy of menstrual blood versus clinician collected cervical samples for detecting high grade (CIN2+ / CIN3+) cervical lesions, which typically require treatment.

 

Their findings are based on 3,068 women aged 20-54 years with regular menstrual cycles, enrolled between September 2021 and January 2025 at four urban and three rural communities in Hubei Province, China.

 

Each participant provided three samples for testing: a menstrual blood sample collected using a minipad - a sterile cotton strip attached to the absorbent area of a standard sanitary pad (index test), a clinician collected cervical sample (comparator test), and an additional clinician collected cervical sample for laboratory processing.

 

A WeChat mobile app (Early Test) was also available to participants to access test results and advice from healthcare providers.

 

The main outcome measure was diagnostic sensitivity and specificity of the tests. Sensitivity indicates how well a test picks up people who have a disease and specificity indicates how well a test picks up those who don’t.

 

Minipad collected samples for HPV testing showed a sensitivity of 94.7% for detecting CIN2+ which was comparable to clinician collected samples (92.1%).

 

Although minipad samples showed a lower specificity than clinician samples (89.1% v 90.0%), the negative predictive value - the probability that a person with a negative test result truly does not have the disease - was identical (99.9%) for both collection methods.

 

There was also no significant difference in positive predictive value - the probability that a person with a positive test result truly has the disease - between both collection methods (9.9% v 10.4%) and referral for further testing (colposcopy) was comparable (10.1 v 9.6 referrals per CIN2+ detected).

 

Integration with the Early Test mobile app further streamlined result reporting and patient communication, enhancing the feasibility of large scale implementation of screening, note the authors.

 

These are observational findings so no firm conclusions can be drawn about cause and effect, and the authors acknowledge several study limitations that warrant careful consideration.

 

However, they say: “The results of this large scale community based study show the utility of using minipad collected menstrual blood for HPV testing as a standardised, non-invasive alternative or replacement for cervical cancer screening.”

 

“The findings of this study support the integration of menstrual blood based HPV testing into national cervical cancer screening guidelines.”

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Journal

The BMJ

DOI

10.1136/bmj-2025-084831 

Method of Research

Observational study

Subject of Research

People

Article Title

Testing menstrual blood for human papillomavirus during cervical cancer screening in China: cross sectional population based study

Article Publication Date

4-Feb-2026

COI Statement

All authors have completed the ICMJE uniform disclosure form at www.icmje.org/disclosure-of-interest/ and declare: support the Key Technology R&D Programme of Hubei and the Academician Expert Workstation of the Central Hospital of Wuhan in China. RSL reports consulting for Organon, Celmatix and Exeltis. All other authors declare no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; and no other relationships or activities that could appear to have influenced the submitted work

 

Are returning Pumas putting Patagonian Penguins at risk? New study reveals the likelihood

University of Oxford

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image: 

A Magellanic penguin carcass showing signs of predation by puma at the Monte León National Park colony. Courtesy of © Joel Reyero 2024

view more 

Credit: © Joel Reyero 2024

More images available via the link in the Notes

 Section

Summary:

• Some Argentinian penguins are experiencing high levels of predation from pumas recolonising their historical territory. A new study has quantified the risk on long-term penguin population survival.

• Over four years, pumas at a national park on the Argentinian Patagonia coast are thought to have killed over 7,000 adult penguins (7.6% of the colony’s adult population) – but left many uneaten.

• Long-term, however, puma predation alone is unlikely to threaten colony viability, while low breeding success and reduced juvenile survival appear to be greater threats to the survival of these penguins.

• The findings have been published today (5 February) in the Journal for Nature Conservation.

 

Should we protect an emblematic species if it may come at the cost of another one – particularly in ecosystems that are still recovering from human impacts? This is the conservation dilemma facing Monte Leon National Park, on the Patagonian coast in Argentina.

Since cattle ranching was abandoned in southern Argentina in 1990, pumas (Puma concolor) have been recolonising their historical ranges in this area. For the first time, this brought them in contact with Magellanic penguins (Spheniscus magellanicus) who had moved to the mainland from nearby islands due to the absence of terrestrial predators. Being largely defenceless, the penguins became an easy target for the large carnivore – but it was unknown up to now the exact impact the pumas were having on penguin population numbers.

Since its creation in 2004, researchers from the Centro de Investigaciones de Puerto Deseado of the Universidad Nacional de la Patagonia Austral and rangers from the Monte Leon National Park have monitored the penguin populations in the Park. Over four years (2007-2010), they counted the number of carcasses caused by puma predation. In the new study, they collaborated with researchers from Oxford University’s Wildlife Conservation Research Unit (WildCRU) to analyse the data.

Based on the numbers of penguins found killed, the research team estimated that more than 7,000 adult penguins were killed over the four-year study, most of which were not fully eaten, indicating that not all the penguins were killed for food. This is roughly 7.6% of the adult population (around 93,000 individuals).

Lead author Melisa Lera, a postgraduate student at WildCRU, Oxford University said: “The number of carcasses showing signs of predation we found in the colony is overwhelming, and the fact that they were left uneaten means pumas were killing more penguins than they required for food. This is consistent with what ecologists describe as ‘surplus killing’. It is comparable to what is seen in domestic cats when prey are abundant and/or vulnerable: ease of capture can lead to cats hunting more birds, even when they do not end up actually eating them. We needed to understand if the penguin colony’s persistence could be threatened due to this behaviour.”

However, when the team carried out modelling on the data, this indicated that pumas alone were unlikely to drive the colony at Monte León Park to extinction. Instead, the colony’s future appears to be far more sensitive to factors such as reproductive success and juvenile survival. Population extinction was projected only under hypothetical scenarios combining low juvenile survival (with around 20% failing to reach adulthood) and very low reproductive output (a maximum of one chick per pair). High puma predation was predicted to exacerbate these outcomes.

Study co-author Dr Jorgelina Marino (WildCRU, Oxford University) said: “This study captures an emerging conservation challenge, where recovering carnivores are encountering novel prey. Understanding how these dietary shifts affect both predators and prey is essential to inform conservation.”

Since the models identified breeding success and mortality of the juveniles as some of the key determinants of population viability, the authors highlight the need to understand how environmental factors such as nutrients, food and temperature - known to be influenced by climate change - may affect the penguins’ reproductive success.

As terrestrial predators continue to expand into coastal environments, further mainland colonies of seabirds and other coastal species may become vulnerable. For instance, non-native feral hogs are now key predators of loggerhead sea turtle eggs along the Georgia coast, USA, whilst coyotes in eastern North America are colonising coastal barrier islands, with impacts across these ecosystems.

The authors emphasise the need for sustained monitoring to detect demographic declines early and to guide management actions to prevent severe ecological consequences. The Park authorities continue to monitor Puma and Penguin populations.

---------------------------------

MLNP Website: Parque Nacional Monte León | Argentina.gob.ar

Notes to editors:

For media enquiries and interview requests, contact Melisa Lera, WildCRU, The University of Oxford, melilera9@gmail.com

The study ‘Shifting predator–prey dynamics at the land–sea interface: The case of Magellanic penguins and pumas’ will be published in Journal for Nature Conservation on Thursday, 5 February at 00:01 GMT/UTC, DOI: https://doi.org/10.1016/j.jnc.2025.127208 To view a copy of the study before this under embargo, contact: Melisa Lera, WildCRU, The University of Oxford, melilera9@gmail.com

Images relating to this release that can be used in articles can be found here:

https://drive.google.com/drive/folders/1dErtmsaJKSuizI7oTxQ6V6YB_C8ewmF6?usp=sharing These are for editorial purposes relating to this press release ONLY and MUST BE credited (see captions file in folder). They MUST NOT be sold on to third parties.

About the University of Oxford

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Infographic of the study's findings. 

Credit: Sarah Markes.

Fieldwork included counting carcasses and measuring body dimensions, to better assess the impacts of puma predation.

 © Esteban Frere 2007

An adult puma leaving the penguin nesting area, and a penguin lies dead behind it. (This study did not collar the pumas). 

Courtesy of © Joel Reyero 2024

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A Magellanic penguin at the nest, built under bushes in Monte León National Park. Courtesy of © Joel Reyero 2024

Journal

Journal for Nature Conservation

DOI

10.1016/j.jnc.2025.127208 

Article Title

Shifting predator–prey dynamics at the land–sea interface: The case of Magellanic penguins and pumas