Cited by 2,804Autism Spectrum Disorder ResearchChild Nutrition and Feeding IssuesSexual Differentiation and Disorders

What Is the Male-to-Female Ratio in Autism Spectrum Disorder? A Systematic Review and Meta-Analysis

Open access
Loomes, Rachel, Hull, Laura, Mandy, William Polmear Locke·2017·Journal of the American Academy of Child & Adolescent Psychiatry

Abstract

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.

The claims and statistics of this paper haven’t been checked yet.

Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.

A few free checks a day · papers already verified open instantly · results are public

Integrity signals

Registry

Crossref · 10.1016/j.jaac.2017.03.013

Cites

86 of 86 references verified0 citation errors · 0 not checkable

Statistics

Claims the paper makes

The claims and statistics of this paper haven’t been checked yet.

Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.

A few free checks a day · papers already verified open instantly · results are public

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • Neurodevelopmental disorders, including autism spectrum disorder, have an increased prevalence in males; boys are approximately three times more likely to be diagnosed than girls.

    “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]

    The cited sentence says boys are approximately three times more likely to be diagnosed than girls. The Discussion instead distinguishes diagnosis from underlying ASD prevalence: it reports about four diagnosed males per female, while its estimate of the true ASD ratio is closer to three to one. The paper supports a male excess in ASD, but not the cited three-to-one figure for diagnoses. (LLM, conf=0.87)

    Checked by a reasoning model — may be wrong.

    Experimental — accuracy not yet measured
  • 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.

    “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

    The Introduction reports that ASD is more commonly diagnosed in males and describes 4:1 as a widely cited estimate from prevalence studies. The Discussion reports an overall pooled odds ratio of 4.20, but argues that the true ratio is below 3.5:1. Our copy does not attribute a 4:1 estimate to the 2010 Global Burden of Disease study. (LLM, conf=0.87)

    Experimental — accuracy not yet measured
  • ASD is more common in males than in females, with reported ratios ranging from 2.1 to 5.1, and an estimate of 4.1 in the 2010 Global Burden of Disease study.

    “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]

    The Introduction states that ASD is more commonly diagnosed in males and that male-to-female ratios vary substantially across epidemiological studies. The cited paper does not report the claimed 2.1–5.1 range or attribute a 4.1 estimate to the 2010 Global Burden of Disease study; its Discussion instead reports a pooled odds ratio of 4.20 from its own meta-analysis. Page numbers were not provided in our copy. (LLM, conf=0.88)

    Experimental — accuracy not yet measured
  • A recent meta-analysis by Loomes et al (2017) estimated a male:female ratio of 3:1, and found that this did not differ greatly by intellectual dis/ability.

    “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)

    The Discussion estimates a male-to-female ratio a little over 3:1 in the more methodologically reliable studies. But the ‘Influences on the ASD Male-to-Female Odds Ratio’ section reports that IQ remained a significant predictor: studies with a higher proportion of autistic participants with intellectual disability had a lower male-to-female ratio. That does not support the claim that the ratio did not differ greatly by intellectual disability. (LLM, conf=0.88)

    Experimental — accuracy not yet measured
  • A recent review and meta-analysis suggests a male:female ratio of 3:1 in ASD.

    “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).”

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

The self-check needs the paper’s full text.

Cites

Flagged first, then by citations

Research works printed but not linked: 2

  1. [11]11. Medical Research Council. MRC review of autism research: Epidemiology and causes. London: Author; 2001.
  2. [26]26. Center for Disease Control. Prevalence of autism spectrum disorders -autism and developmental disabilities monitoring network, 14 sites, United States, 2008. MMWR Surveill Summ. 2012;61:1-19.

Cited by

Sorted by citations

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 · 2014: 1 · 2012: 1
FWCI
18.91
Type
journal article
Language
en
Open access
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
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › 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

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review