The argument for including women in clinical research should not need to be made in 2026. And yet here we are.
Decades after the NIH Revitalization Act of 1993 mandated the inclusion of women and minorities in federally funded clinical trials, the research literature still skews male. Disease presentations studied predominantly in men produce treatment protocols calibrated to male physiology. Women receive those treatments — at male-calibrated doses, with male-calibrated expectations — and the results are predictably worse.
The Biological Reality
Sex is not a confounding variable to be controlled away. It is a fundamental dimension of human biology.
Women metabolize drugs differently than men. Hormones affect immune function, cardiovascular risk, pain processing, and neurological responses in ways that interact with virtually every therapeutic intervention. Autoimmune diseases — which affect women at two to three times the rate of men — involve immune mechanisms that are themselves sex-differentiated. The same pathology presents differently in a female body.
When clinical trials treat “the patient” as implicitly male and then attempt to generalize findings to women, they are not doing science. They are doing assumption.
What the Data Actually Show
A review published in the Journal of Women’s Health found that women are still underrepresented in cardiovascular trials despite heart disease being the leading cause of death in women. Women have been excluded from oncology trials at rates that cannot be explained by clinical criteria. Pain research — a field with direct implications for tens of millions of women — has historically used overwhelmingly male animal models.
The consequences are measurable. Women experience adverse drug reactions at nearly twice the rate of men, in part because standard dosing has been calibrated to male-typical metabolism. Women are more likely to have their symptoms dismissed, misdiagnosed, or undertreated — in part because the evidence base clinicians rely on was not built with women’s bodies in mind.
The Current Opportunity — and the Current Threat
The NIH Office of Research on Women’s Health (ORWH), established in 1990 after sustained advocacy from researchers and women’s health organizations, has been central to the effort to correct these imbalances. The NIH’s 2016 policy requiring researchers to account for sex as a biological variable in preclinical research was a meaningful step.
Both are now under pressure. The proposed FY2027 budget includes no explicit protections for ORWH funding, and the broader environment of federal research cuts threatens the infrastructure that has driven progress on sex differences research over the past three decades.
Meaningfully including women in clinical trials is not simply a matter of fairness. It is a scientific imperative to improving health outcomes for more than half the population. Research that systematically excludes or underpowers women does not just fail those women — it fails the scientific enterprise.
What Disruption Looks Like Here
The path forward requires several things happening simultaneously:
Regulatory pressure. The FDA has tools it has used inconsistently. Sex-disaggregated data should be required in drug applications, not optional. Post-market surveillance should systematically track sex-differentiated outcomes.
Funding clarity. Congressional appropriators who are serious about research integrity should explicitly protect ORWH funding and the sex-as-biological-variable policy in any spending legislation.
Institutional accountability. Academic medical centers and pharmaceutical companies that claim commitment to equity need to show their trial enrollment data — by sex, race, and age — as a standard disclosure.
Clinical education. Physicians practicing with treatment protocols derived primarily from male subjects need to know that. Medical school curricula need to teach sex differences as a core, not an elective.
The science is not the hard part. The hard part is building the institutional will to do it.
