Note: This article refers to “women” and to “female bodies.” The author acknowledges that those are not interchangeable terms. “Women” refers to a social category—people perceived to be and treated as women. “Female bodies” refers to bodies marked by particular internal and external sexual organs, chromosomal makeup, and hormonal composition. However, the exclusion of female bodies from biomedical research is intertwined with historical social devaluation of women; this interdependence informs the following article.

Biomedical science seems to have chronic amnesia: The institution as a whole seems to forget that women are people, too. Biomedical and pharmaceutical research often over-represents male bodies and assumes that the male default is an appropriate stand-in for all human beings. And that isn’t simply annoying and degrading in that it erases and renders invisible about half the human population.

It’s not just frustrating that the largest study on “normal human aging” didn’t include women for the first 20 years of its existence, or that the entirety of the Physicians Health Study (popularly known as the “baby aspirin study”) on the effects of aspirin and beta-carotene on heart health failed to include women. It’s dangerous to exclude women. It’s actively harmful—deadly, even—because, in many contexts, female bodies work differently from male bodies in ways that have important ramifications for medical testing, diagnosis, and treatment.

Women have historically been underrepresented in biomedical research, often excluded from studies altogether. Diseases predominantly affecting women receive significantly less funding and attention from researchers than diseases disproportionately affecting men or diseases perceived to be sex-neutral. For example, myalgic encephalomyelitis, also known as chronic fatigue syndrome (ME/CFS), predominantly affects women and receives less than 3% of the average amount of annual research funding for a single disease category from the National Institutes of Health.

This means we have significant knowledge gaps when it comes to women’s health, female bodies, and the effects of a host of illnesses and treatments on women. Although, there a couple of fields of research in which women are actually overrepresented (drumroll, please): anti-wrinkle studies and studies on child health, where data on mothers is collected, but not fathers.

That doesn’t mean that there haven’t been attempts to change the status quo, but progress has been slow and unsteady. Here are some of the “Greatest Hits” (brace yourself, it’s depressing):

From 1977 to 1993: The Food and Drug Administration (FDA), which, among other things, reviews applications for new pharmaceuticals, explicitly prohibited women “of childbearing potential” from participating in early phase clinical trials, which discouraged researchers from including women in any phase of research. Most clinical research in the U.S. is conducted by private pharmaceutical companies.

1985: The National Institutes of Health (NIH), which is the largest public source of funding for biomedical research, attempted (largely unsuccessfully) to address the issue of sex representation in medical research.

1990: The Society for the Advancement of Women’s Health Research (SWHR) demanded an audit of the NIH by the U.S. Government Accountability Office (GAO), which prompted the NIH to establish the Office of Research on Women’s Health (ORWH), mandate the inclusion of women as research subjects in NIH-funded research, and launch the Women’s Health Initiative, a large-scale study of the effects of hormone therapy on women. But the study was terminated early with a warning to the public that hormone therapy causes breast cancer—even though the identified risk was not statistically significant and despite preliminary findings of significant benefits for heart health, among other things.

1992: The FDA started mandating the inclusion of women in clinical drug trials, but didn’t specify how many women should be included and didn’t require analyses of the differences in the effects of a test drug on male and female research participants (or “sex disaggregated” data). This is still the case today.

1993: The NIH Revitalization Act established the ORWH as a permanent department of the NIH and mandated that NIH-funded studies include enough women to conduct sex disaggregated analyses. The Act also set aside funds for research on conditions that predominantly affect women.

2000: A GAO report found that NIH-funded studies were still failing to report sex disaggregated data.

2004: The first U.S. textbook on gender-specific medicine was published. Fun fact: a 2013 study of 59 medical textbooks found that the anatomy vulva was either inadequately, incompletely, or incorrectly described in all the studied texts. And, as of 2019, medical textbooks still inaccurately represent the nerves and vasculature of the clitoris.

2010: Independent studies found that most published biomedical research still did not include women or report sex disaggregated data.

2013: About 70% of medical schools in the U.S. and Canada still had virtually no curriculum coverage of sex differences.

2014: The previous NIH mandate only required women’s inclusion in human participant studies and particular late phases of research. In October 2014, the NIH started rolling out rules requiring inclusion of female cells and animals in earlier phases of research.

2015: A GAO report recommended increased FDA oversight of the inclusion of women in clinical trials, given the FDA’s inability to monitor compliance with safety regulations. For instance, new drug applications could contain evidence that a drug might affect male and female bodies differently but fail to contain dose adjustment recommendations, and this did not prevent drug approval.

2015: Independent studies found that women continued to be underrepresented in research.

2023: A study published September of this year found that failure to present sex disaggregated data continues to be a serious problem.

The bad news is clear: progress has been slow and hard to come by. And when we don’t have enough high-quality information about women’s health, we end up with an unacceptable risk of misdiagnosis and poor treatment. As I wrote last month, that can be quite costly (literally and figuratively) for all of us—from individuals, to their families, to the healthcare system, to society as a whole.

The good news, though, is that the battle cry for research on women’s health and specifically for sex disaggregated data is strong. We’ve started accumulating some useful information about female bodies: Female bodies don’t respond to general anesthesia the same way male bodies do; the menstrual cycle affects immune response, vaccination side effects, reactions to pharmaceuticals, and the risk of heart disease; hormone concentrations affect the risk of ACL injury; and asthma presents differently in female bodies. Notably, since November 2019, the Apple Women’s Health Study has been collecting data (which they are sex disaggregating!) to study the connection between menstruation, polycystic ovarian syndrome, and heart health.