SWHR’s goal is for sex differences to be integrated as an essential element of all research.

Sex differences studies are an area of research that seeks to uncover the biological and physiological differences between men and women. Scientists have long known of the anatomical differences between men and women, but only within the past decade have they begun to uncover significant biological and physiological differences between the sexes.


The path to sex differences research legislation began in 1993 when President Bill Clinton signed the National Institutes of Health (NIH) Revitalization Act. The legislation, written with input from SWHR, mandated that women and minorities be included in all clinical research and required that Phase III clinical trials be analyzed by sex. That same year, SWHR succeeded in advocating for a Government Accountability Office (GAO) examination of the FDA, which concluded that it had not effectively overseen sex differences data.

In 2001, the Institute of Medicine released a report, initiated and supported by SWHR, that reinforced a need for sex differences research. This groundbreaking research was the first significant review of the status of sex and gender differences in biomedical research by an independent research organization, and determined that sex matters for the entire body throughout the entire lifespan.

However, despite the IOM report, SWHR reported in 2005 that NIH support of research on biological health differences between women and men remained insufficient.

In 2012, The Food and Drug Administration Safety and Innovation Act (FDASIA) was signed into law, requiring the FDA to provide a special report and accounting of trials by sex, race, and ethnicity, and in 2015, the NIH moved to include sex as a biological variable in future research. SWHR continues to advocate for increased sex differences research.

View SWHR’s timeline of women’s health research »

Why it matters:

The differences between men and women at a biological level affect women’s everyday lives, from the drugs they take to the way they interact with their environment. In order for women to be safe and healthy, the differences between men and women must be continually studied. Between 1997 and 2001, 8 out of 10 prescription drugs pulled from the US market caused greater health risks for women. With increased sex and gender differences research, we can prevent these dangerous oversights from happening at all.

Read about 10 differences that make a difference in women’s health »

Women need to be included in the early phases of clinical trials, when safety and pharmacological activities are addressed, and the inclusion of female cells and animals in pre-clinical trials will shed light on important sex differences even earlier. The FDA should require that research that accompanies an application for a new drug, device or biologic have the appropriate representation of women and minorities in all phases of research. Improvements to research should carry through to scholarly journals, which should require a statement on whether or not sex was examined as part of the research and if any biological sex difference was noted in the analysis.

What SWHR is doing:

Research: In order to promote the research of sex and gender differences, SWHR has hosted scientific roundtables on subjects like sleep and Alzheimer’s. SWHR’s interdisciplinary networks have built research capacity of the study of sex differences.

Legislative action: SWHR has advocated for increased women’s health research funding and policies that promote sex differences research by providing Congressional testimony, hosting briefings, and submitting policy letters.

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