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XX or XY: Medical Journals Should Report Sex Differences

By Phyllis Greenberger, MSW, Leslie Ritter, MA, and Emily Grant, for Society for Women's Health Research

It is no secret that men and women are fundamentally different, yet historically most research has assumed that men and women are the same. The average American still does not fully recognize that being biologically male or female impacts the way they develop diseases and the way medical treatments affect their bodies.

The Society for Women's Health Research (SWHR) welcomes the recent policy changes by the National Institutes of Health to establish guidelines requiring the inclusion of both female and male cells and animals in preclinical studies that are looking at diseases that affect both women and men.

Additionally and crucially, many research journals have recognized the importance of sex differences in biomedical research and are implementing policies to improve the reporting of sex differences in their publications. In fact, The Endocrine Society recently announced that they have introduced policies to improve the reporting of the sex of research subjects. [1] We applaud The Endocrine Society this important step, and we urge all journals and publications to implement similar policies.

In 2010, SWHR conducted an informal survey of 11 popular science and medical journals to see if any had guidelines supporting sex differences research and analysis and found that only two—Journal of the National Cancer Institute and Circulation—required any sex-differences reporting for publication. As of 2014 the number of peer-reviewed medical journals that had guidance on sex differences reporting had grown to 28. [2] This trend is promising, yet much work remains to ensure that sex differences are being properly examined and that these differences become part of the health conversation.

Currently, there are no universal standards regarding requirements for sex analysis, and guidelines fluctuate from giving "extra credit" toward publication for articles that disclose the sex of test subjects to detailed requirements for the inclusion of and reporting on sex differences. In addition to journals granting this "extra credit," SWHR believes they should require the following information for publication:

  • The numbers of women and men tested should be identified in all research stages.
  • Studies that examine either women or men should specify which sex was studied in the title of the research article.
  • Sex-identified raw data should be published to provide the building blocks for future research directions.
  • Sex-stratified analyses should be included for publication when relevant to the research topic along with notation of sex included in the analysis.
  • Indication of whether or not studies have conducted a power analysis to determine the minimum number of male and female subjects whether cells, animals or humans requiring inclusion in order to potentially detect statistically significant differences between study groups.

Historically, medical research, from preclinical studies to early stage human subject trials, was tested almost exclusively on males. In 1993, SWHR worked to ensure that females were mandated in Phase III trials for federally funded research. However, privately funded research is not subject to this mandate, meaning that medications available to all Americans can be designed and tested based on what is deemed safe and effective for males, either because females have not been included in sufficient numbers during clinical trials or because an analysis of sex differences was not done.

It has been proven that women suffer more side effects than men [3] and metabolize drugs differently from men, [4] so it is imperative that researchers know that differences must be captured and analyzed before products come on the market, in order to properly ensure that individuals are not put at unnecessary risk. The health and safety of all Americans is dependent on biomedical research being conducted and analyzed on both sexes appropriately.


  1. The Endocrine Society. "Endocrine Society Strengthens Sex-Difference Reporting Requirements for Scholarly Journals." Accessed December 5, 2014.
  2. Gendered Innovations. Sex and Gender Analysis Policies of Peer-Reviewed Journals. Accessed December 5, 2014.
  3. GAO. Drug Safety: Most drugs withdrawn in recent years had greater health risks for women. 2001; GAO-01-286R: Accessed December 5, 2014.
  4. Whitley H, Lindsey W. Sex-based differences in drug activity. American Family Physician. 2009;80(11):1254-1258. PubMed PMID: 19961138. Accessed December 5, 2014.

Society for Women's Health Research is the national thought leader in the study of sex differences, dedicated to transforming women’s health through science, advocacy and education.

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