Definition and research guide
This page combines a MeSH definition, publication statistics and selected research abstracts. It is a starting point for reading the literature, not a medical textbook or a systematic evidence review.
Content available: 4 complete abstracts (537 words), 10 references. Full article text is not stored or reproduced here; follow the PMID, DOI or PMC links to read the original sources and their access terms.
Definition
The number of males and females in a given population. The distribution may refer to how many men or women or what proportion of either in the group. The population is usually patients with a specific disease but the concept is not restricted to humans and is not restricted to medicine.
Definition: NLM Medical Subject Headings (MeSH) scope note (Public domain (U.S. National Library of Medicine); attribution requested). View the MeSH record.
Also known as: Distribution, Sex; Distributions, Sex; Sex Distributions.
Where it fits in the MeSH classification
- Broader topics
- Demography
- Narrower topics
- Sex Ratio
Research landscape
PubMed indexes 68,203 records tagged with the MeSH heading “Sex Distribution” (counts retrieved 2026-10-31). 4,112 of them (6.0%) were published from 2020 onward, and the busiest period so far is 2000-2009 with 26,601 records.
Reviews account for 4,401 records (6.5%) and meta-analyses for 544. Randomized controlled trials number 600 (0.9%) as a share of all records on the topic. Randomized trials make up only a small share of this literature, so much of what is known comes from laboratory, observational or descriptive work.
Show the data
| Period | Records |
|---|---|
| through 1999 | 11,735 |
| 2000-2009 | 26,601 |
| 2010-2019 | 25,755 |
| 2020 onward | 4,112 |
Publication-type chart data
| Type | Records | Share |
|---|---|---|
| Reviews | 4,401 | 6.5% |
| Meta-analyses | 544 | 0.8% |
| Randomized controlled trials | 600 | 0.9% |
Method: PubMed query "Sex Distribution"[MeSH Terms] with publication-type and date filters, retrieved 2026-10-31.
Reading the evidence in public health and nutrition
Population and nutrition studies mostly observe what people eat, breathe or are exposed to and then look for links with health, which shows association and not proof of cause. Self-reported diet is imprecise, people who eat or live differently also differ in other ways, and effects measured across a population may not apply to one person. Check the study design, how exposure was measured, what else was accounted for and the size of the effect, not only whether it was statistically significant.
Evidence from open-access studies
These open-access studies come from PubMed’s best-match results for this heading (papers whose main topic it is), ranked here by citation count, with one recent addition. Each abstract is reproduced in full under its recorded open licence so that you can read the authors’ own words. They illustrate the literature; they are not a systematic summary of it. Citation counts measure attention, not reliability or clinical benefit.
| Study / authors | Year | Source label / design | Europe PMC citations | Licence / source |
|---|---|---|---|---|
| A 10-year follow-up study of sex inclusion in the biological sciences | 2020 | Research article Design not recorded in structured metadata | 254 | cc by PMID 32513386 · DOI · PMC7282816 |
| Sex differences in SARS-CoV-2 infection rates and the potential link to prostate cancer | 2020 | Review article Design not recorded in structured metadata | 116 | cc by PMID 32641750 · DOI · PMC7343823 |
| Sex Bias in Differentiated Thyroid Cancer | 2021 | Review article Design not recorded in structured metadata | 65 | cc by PMID 34884794 · DOI · PMC8657786 |
| No evidence of sex-ratio meiotic drive associated with the X-linked In(1)Be inversion in Drosophila melanogaster | 2026 | Research article Design not recorded in structured metadata | 0 | cc by PMID 42496986 · DOI · PMC13535459 |
A 10-year follow-up study of sex inclusion in the biological sciences [1]
Abstract reading summary — source excerpts
- Opening excerpt
- In 2016, to address the historical overrepresentation of male subjects in biomedical research, the US National Institutes of Health implemented a policy requiring investigators to consider sex as a biological variable.
- Closing excerpt
- Together, these data demonstrate that while sex-inclusive research practices are more commonplace, there are still gaps in analyses and reporting of data by sex in many biological disciplines.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (171 words)
In 2016, to address the historical overrepresentation of male subjects in biomedical research, the US National Institutes of Health implemented a policy requiring investigators to consider sex as a biological variable. In order to assess the impact of this policy, we conducted a bibliometric analysis across nine biological disciplines for papers published in 34 journals in 2019, and compared our results with those of a similar study carried out by Beery and Zucker in 2009. There was a significant increase in the proportion of studies that included both sexes across all nine disciplines, but in eight of the disciplines there was no change in the proportion studies that included data analyzed by sex. The majority of studies failed to provide rationale for single-sex studies or the lack of sex-based analyses, and those that did relied on misconceptions surrounding the hormonal variability of females. Together, these data demonstrate that while sex-inclusive research practices are more commonplace, there are still gaps in analyses and reporting of data by sex in many biological disciplines.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 32513386 · DOI · PMC7282816
Sex differences in SARS-CoV-2 infection rates and the potential link to prostate cancer [2]
Abstract reading summary — source excerpts
- Opening excerpt
- The recent outbreak of infections and the pandemic caused by SARS-CoV-2 represent one of the most severe threats to human health in more than a century.
- Closing excerpt
- Such information will be indispensable in the current and post-pandemic scenarios.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (103 words)
The recent outbreak of infections and the pandemic caused by SARS-CoV-2 represent one of the most severe threats to human health in more than a century. Emerging data from the United States and elsewhere suggest that the disease is more severe in men. Knowledge gained, and lessons learned, from studies of the biological interactions and molecular links that may explain the reasons for the greater severity of disease in men, and specifically in the age group at risk for prostate cancer, will lead to better management of COVID-19 in prostate cancer patients. Such information will be indispensable in the current and post-pandemic scenarios.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 32641750 · DOI · PMC7343823
Sex Bias in Differentiated Thyroid Cancer [3]
Abstract reading summary — source excerpts
- Opening excerpt
- Differentiated thyroid cancers are more frequent in women than in men.
- Closing excerpt
- On the other hand, the worse prognosis of thyroid cancer associated with the male gender is poorly explained.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (93 words)
Differentiated thyroid cancers are more frequent in women than in men. These different frequencies may depend on differences in patient's behavior and in thyroid investigations. However, an impact on sexual hormones is likely, although this has been insufficiently elucidated. Estrogens may increase the production of mutagenic molecules in the thyroid cell and favor the proliferation and invasion of tumoral cells by regulating both the thyrocyte enzymatic machinery and the inflammatory process associated with tumor growth. On the other hand, the worse prognosis of thyroid cancer associated with the male gender is poorly explained.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 34884794 · DOI · PMC8657786
No evidence of sex-ratio meiotic drive associated with the X-linked In(1)Be inversion in Drosophila melanogaster [4]
Abstract reading summary — source excerpts
- Opening excerpt
- Sex-ratio (SR) X chromosomes are selfish genetic elements that increase the rate of X chromosome transmission in species with a heterogametic sex, violating Mendel's first law of segregation.
- Closing excerpt
- In our experiments, we found no significant differences in SR between karyotype or across our generated lines, suggesting that in the genetic background we used, there is no SR phenotype associated with the In(1)Be inversion.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (170 words)
Sex-ratio (SR) X chromosomes are selfish genetic elements that increase the rate of X chromosome transmission in species with a heterogametic sex, violating Mendel's first law of segregation. In particular, heterogametic males carrying SR X chromosomes produce a greater number of X-bearing sperm than Y-bearing sperm and thus produce a greater number of female than male offspring. SR X chromosomes have been observed in several taxa, including multiple Drosophila species. However, no convincing examples of a strong SR X chromosome have been identified in Drosophila melanogaster. There have been few reports of weak SR X chromosomes segregating in D. melanogaster, including speculation of the X-linked inversion In(1)Be being associated with an SR phenotype. We sought to investigate if the In(1)Be inversion is associated with an SR by measuring the offspring SR in genetically controlled experiments. In our experiments, we found no significant differences in SR between karyotype or across our generated lines, suggesting that in the genetic background we used, there is no SR phenotype associated with the In(1)Be inversion.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42496986 · DOI · PMC13535459
Key reviews and meta-analyses
The most cited review-type papers among PubMed’s best-match results for this heading, listed with bibliographic details only. Follow the links for the full text and access terms.
- Research article Sex and gender: modifiers of health, disease, and medicine [5]
- Research article Sex differences and the epidemiology of depression [6]
- Research article The use of multiple cues in mate choice [7]
- Research article Parental investment, sexual selection and sex ratios [8]
- Research article The effects of China's universal two-child policy [9]
- Research article Birth cohort trends in the global epidemiology of alcohol use and alcohol-related harms in men and women: systematic review and metaregression [10]
References
- Woitowich NC, Beery A, Woodruff T. A 10-year follow-up study of sex inclusion in the biological sciences. . 2020. PMID 32513386 · DOI · PMC7282816
- Chakravarty D, Nair SS, Hammouda N, Ratnani P, Gharib Y, Wagaskar V, et al.. Sex differences in SARS-CoV-2 infection rates and the potential link to prostate cancer. . 2020. PMID 32641750 · DOI · PMC7343823
- Suteau V, Munier M, Briet C, Rodien P. Sex Bias in Differentiated Thyroid Cancer. . 2021. PMID 34884794 · DOI · PMC8657786
- An ME, Begun DJ. No evidence of sex-ratio meiotic drive associated with the X-linked In(1)Be inversion in Drosophila melanogaster. . 2026. PMID 42496986 · DOI · PMC13535459
- Mauvais-Jarvis F, Bairey Merz N, Barnes PJ, Brinton RD, Carrero JJ, DeMeo DL, et al.. Sex and gender: modifiers of health, disease, and medicine. Lancet. 2020. PMID 32828189 · DOI · PMC7440877
- Weissman MM, Klerman GL. Sex differences and the epidemiology of depression. Arch Gen Psychiatry. 1977. PMID 319772 · DOI
- Candolin U. The use of multiple cues in mate choice. Biol Rev Camb Philos Soc. 2003. PMID 14700392 · DOI
- Kokko H, Jennions MD. Parental investment, sexual selection and sex ratios. J Evol Biol. 2008. PMID 18462318 · DOI
- Zeng Y, Hesketh T. The effects of China's universal two-child policy. Lancet. 2016. PMID 27751400 · DOI · PMC5944611
- Slade T, Chapman C, Swift W, Keyes K, Tonks Z, Teesson M. Birth cohort trends in the global epidemiology of alcohol use and alcohol-related harms in men and women: systematic review and metaregression. BMJ Open. 2016. PMID 27797998 · DOI · PMC5093369
About this article
- Sources
- NLM Medical Subject Headings (definition, synonyms); NCBI PubMed (counts, identifiers); Europe PMC (open-access abstracts and citation counts).
- Verification
- Every reference was resolved against PubMed on 2026-11-04; title, year and DOI matched.
- Review state
- automated source verified; no human expert review has been recorded yet.
- Version
- 1, last updated 2026-11-04.
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Evidence strength
EvidenceHelix's computed view of the study designs behind this topic: how common meta-analyses, randomized trials and reviews are, how recent the literature is, and a plain-language reading. It describes the design mix of the literature. It is not a quality appraisal of any study, and it is not medical advice.