The DOI matches its Crossref record; 85 of the 86 references it cites were found in a registry or an index.
What Is the Male-to-Female Ratio in Autism Spectrum Disorder? A Systematic Review and Meta-Analysis
Open accessAbstract
Objective To derive the first systematically calculated estimate of the relative proportion of boys and girls with autism spectrum disorder (ASD) through a meta-analysis of prevalence studies conducted since the introduction of the DSM-IV and the International Classification of Diseases, Tenth Revision.Method Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed. The Medline, Embase, and PsycINFO databases were searched, and study quality was rated using a risk-of-bias tool. Random-effects meta-analysis was used. The pooled outcome measurement was the male-to-female odds ratio (MFOR), namely the odds of being male in the group with ASD compared with the non-ASD group. In effect, this is the ASD male-to-female ratio, controlling for the male-to-female ratio among participants without ASD.Results Fifty-four studies were analyzed, with 13,784,284 participants, of whom 53,712 had ASD (43,972 boys and 9,740 girls). The overall pooled MFOR was 4.20 (95% CI 3.84-4.60), but there was very substantial between-study variability (I 2 = 90.9%). High-quality studies had a lower MFOR (3.32; 95% CI 2.88-3.84). Studies that screened the general population to identify participants regardless of whether they already had an ASD diagnosis showed a lower MFOR (3.25; 95% CI 2.93-3.62) than studies that only ascertained participants with a pre-existing ASD diagnosis (MFOR 4.56; 95% CI 4.10-5.07).Conclusion Of children meeting criteria for ASD, the true male-to-female ratio is not 4:1, as is often assumed; rather, it is closer to 3:1. There appears to be a diagnostic gender bias, meaning that girls who meet criteria for ASD are at disproportionate risk of not receiving a clinical diagnosis.
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In the citing paper
“Neurodevelopmental disorders, including autism spectrum disorder (ASD), have an increased prevalence in males. Boys are approximately three times more likely to be diagnosed than girls [119].”
From Air pollution and children’s health—a review of adverse effects associated with prenatal exposure from fine to ultrafine particulate matter (2021) · cites this paper as [119]
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Experimental — accuracy not yet measuredThe source backs part of the claim, not all of it — or backs it for a different population, condition or comparison.
In the citing paper
“Epidemiological studies indicate that ASD is more common among males than females, with a ratio estimate from the 2010 Global Burden of Disease study revealing a ratio of 4:1 (Brugha et al. 2016; Loomes et al. 2017).”
From The Diagnosis of Autism: From Kanner to DSM-III to DSM-5 and Beyond (2021) · cites this paper as Loomes et al. 2017
Experimental — accuracy not yet measuredThe source backs part of the claim, not all of it — or backs it for a different population, condition or comparison.
In the citing paper
“Epidemiological administrative and community-based [Au:OK?YES] studies have suggested that ASD is more common in males than in females, with reported ratios [Au:OK to add 'with reported ratios' here?] ranging from 2.1 -5. 1, with an estimate of 4.1 in the 2010 [Au:OK?] Global Burden of Disease study 3,4 .”
From Autism spectrum disorder (2020) · cites this paper as [3]
Experimental — accuracy not yet measuredThe source backs part of the claim, not all of it — or backs it for a different population, condition or comparison.
In the citing paper
“A recent meta-analysis by Loomes et al (2017) estimated a male:female ratio of 3:1, and importantly found that this did not differ greatly by intellectual dis/ability.”
From Annual Research Review: Looking back to look forward – changes in the concept of autism and implications for future research (2020) · cites this paper as Loomes et al (2017)
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In the citing paper
“Historically, ASD has been thought of as a predominantly male disorder, with a recent review and meta-analysis suggesting a male:female ratio of 3:1 (Loomes et al. 2017).”
From Barriers to Autism Spectrum Disorder Diagnosis for Young Women and Girls: a Systematic Review (2021) · cites this paper as Loomes et al. 2017
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In the citing paper
“There are increasing concerns that autistic females are being missed, diagnosed later than males or misdiagnosed (Giarelli et al. 2010; Holtmann et al. 2007; Loomes et al. 2017; Shattuck et al. 2009).”
From Barriers to Autism Spectrum Disorder Diagnosis for Young Women and Girls: a Systematic Review (2021) · cites this paper as Loomes et al. 2017
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In the citing paper
“This result was consistent with a previous meta-analysis which showed that studies reporting registry and administrative prevalence produced a substantially higher sex ratio than studies relying on active case finding.27”
From The global epidemiology and health burden of the autism spectrum: findings from the Global Burden of Disease Study 2021. (2025) · cites this paper as [27]
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In the citing paper
“For the whole group of ASD, the obtained estimate is equal to the proportions found in the systematic review of the ASD prevalence performed by Zeidan et al. (18) and in the meta-analysis of Loomes et al. (93), focusing specifically on the male-to-female ratio.”
From The global prevalence of autism spectrum disorder: A three-level meta-analysis (2023) · cites this paper as Loomes et al. (93)
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In the citing paper
“This meta-analysis illustrated a potential sex bias for receiving diagnoses of autism spectrum disorder”
From The global epidemiology and health burden of the autism spectrum: findings from the Global Burden of Disease Study 2021. (2025) · cites this paper as [27]
In the citing paper
“We cannot, however, distinguish the female protective effect due to common or rare variants from diagnostic bias in the current study24,51.”
From Genetic correlates of phenotypic heterogeneity in autism (2022) · cites this paper as [51]
In the citing paper
“This difference was observed across a range of prevalence estimates (Fig. 7c and Supplementary Table 19) after downsampling the number of autistic males to match the number of autistic females (Supplementary Table 18) and varying the male:female ratio to 3.3:1 to account for diagnostic bias51 (Supplementary Table 18).”
From Genetic correlates of phenotypic heterogeneity in autism (2022) · cites this paper as [51]
In the citing paper
“Several social factors can influence diagnosis in a sex-differential manner”
From Genetic correlates of phenotypic heterogeneity in autism (2022) · cites this paper as [51]
In the citing paper
“to account for diagnostic bias that may inflate the ratio.”
From Genetic correlates of phenotypic heterogeneity in autism (2022) · cites this paper as [51]
In the citing paper
“Autism spectrum disorder (ASD) is diagnosed three to four times more frequently in males than in females.1, 2, 3”
From The female protective effect against autism spectrum disorder (2022) · cites this paper as [3]
In the citing paper
“One well-known influence is diagnostic bias, which may occur for many reasons, including societal norms of behavior, bias in assessment tools, the sex of evaluators, misdiagnosis of female cases, better “masking” of autistic traits in females, and sex differences in internal and externalizing features of autism.3,33”
From The female protective effect against autism spectrum disorder (2022) · cites this paper as [3]
In the citing paper
“Autism spectrum disorder (ASD) is a behaviorally defined condition predominantly found in males [10, 19, 40, 49].”
From Linguistic camouflage in girls with autism spectrum disorder (2017) · cites this paper as [40]
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Citations
Cites
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Forming inferences about some intraclass correlation coefficients.
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A Re-Evaluation of Random-Effects Meta-Analysis
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1 of the 86 references couldn’t be matched to a known paper.
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- 2014, Prevalence of autism spectrum disorders—autism and developmental disabilities monitoring network, 11 sites, United States, 2010, MMWR Surveill Summ, 63, 1
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Hu, D.-X., Lu, C.-M., Si, X.-Y., Wu, Q.-T., Wu, L.-H., Zhong, H.-J., & He, X.-X. (2025) · Frontiers in Pediatrics · doi:10.3389/fped.2025.1528167 · Cited by 10
Association between early androgens and autistic traits: A systematic review and meta-analysis
Coscini, N., Williams, K., Chew, D., Pang, K. C., O’Connell, M. A., & May, T. (2021) · Research in Autism Spectrum Disorders · doi:10.1016/j.rasd.2021.101789 · Cited by 10
Using Art-Based Acceptance and Commitment Therapy (ACT) for an Adolescent With Anxiety and Autism
Chapman, R., & Evans, B. (2020) · Clinical Case Studies · doi:10.1177/1534650120950527 · Cited by 12
Liu, W., Shah, N., Ma, I., & Rosenblau, G. (2024) · Developmental Science · doi:10.1111/desc.13463 · Cited by 6
Metadata
- Authors
- Loomes, R., Hull, L., & Mandy, W. P. L.
- Affiliations
- University College London (GB)
- Venue
- Journal of the American Academy of Child & Adolescent Psychiatry
- Publisher
- Elsevier BV
- Published
- 2017-06
- Volume
- 56
- Issue
- 6
- Pages
- 466-474
- ISSN
- 0890-8567 (ISSN-L)
- OpenAlex
- W2604697269
- Cited by
- 2,804
- References
- 86
- Citations by year
- 2026: 371 · 2025: 334 · 2024: 398 · 2023: 355 · 2022: 357 · 2021: 366 · 2020: 331 · 2019: 177 · 2018: 91 · 2017: 19
- FWCI
- 18.91
- Type
- journal article
- Language
- en
- Open access
- green
- discovery.ucl.ac.uk
- Locations
- Journal of the American Academy of Child & Adolescent Psychiatry (publishedVersion)
- PubMed (publishedVersion)
- UCL Discovery (University College London) (submittedVersion)
- Explore Bristol Research (submittedVersion)
- Topics
- Life Sciences › Neuroscience › Cognitive Neuroscience › Autism Spectrum Disorder Research
- Health Sciences › Medicine › Psychiatry and Mental health › Child Nutrition and Feeding Issues
- Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Sexual Differentiation and Disorders
- Keywords
- autism spectrum disorder, sex ratio, male-to-female ratio, prevalence, risk of bias
- MeSH terms
- Autism Spectrum Disorder, Cross-Sectional Studies, Female, Humans, Male, Population Surveillance, Sex Factors
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