For decades, the clinical trial system treated women as an afterthought, too “complicated,” too “at risk,” and ultimately too excluded. The result? A pharmaceutical landscape built on data that doesn’t fully reflect half the population. While policies like the 1993 National Institutes of Health (NIH) Revitalization Act opened the door to inclusion,1 we're still far from equity, especially in early-phase trials, sex-specific data analysis, and the safe treatment of pregnant women. But this isn’t just a matter of fairness, it’s a matter of science, safety, and smart business. With a $60B women’s health market on the horizon,2 the companies who lead on inclusive trial design won’t just do better by women; they’ll do better, period.
For most of modern medical history, the “average patient” has looked suspiciously like a 70-kilogram white male, even when the medication was intended for, say, a menopausal woman with a completely different hormonal profile, metabolism, and lived experience. And while that may sound like an outdated stereotype, it’s disturbingly recent history.
Until 1993, women, particularly those of childbearing potential, were routinely excluded from clinical trials. The logic? Hormonal variability made the data “messy.” Pregnancy risks were inconvenient. In short, female bodies were seen as too complex to include, so they were left out entirely. What followed was decades of drug development, dosing guidelines, and safety protocols built for one demographic, with the assumption that everyone else would simply adjust.
It didn’t work. It still doesn’t.
The 1993 Wake-Up Call (That Shouldn’t Have Taken That Long)
The turning point came in the form of legislation: the NIH Revitalization Act of 1993, which made the inclusion of women and minorities in NIH-funded research mandatory.1 No more “optional diversity.” No more shrugging off half the population as a variable to control for. This was the moment when clinical research had to face a hard truth: medicine that doesn’t work for women doesn’t work.
Since then, progress has been made. But before we celebrate too loudly, let’s talk about the fine print.
The Progress: Real, Measurable… and Not Nearly Enough
Women now make up over half of NIH-funded clinical trial participants.3
The NIH’s “Sex as a Biological Variable” (SABV) policy ensures sex differences are factored into study design and analysis.4
Landmark studies like the Women’s Health Initiative, with over 160,000 participants, have redefined our understanding of women’s cardiovascular disease, cancer, osteoporosis, and more.5
In 2023, the FDA formed a task force focused on including pregnant and lactating populations in trials, a major move to fill a long-ignored gap.6
Meanwhile, AI and decentralized trial technologies are helping reduce bias and expand accessibility, streamlining recruitment without sacrificing demographic representation.
Still, inclusion on paper isn’t the same as inclusion in practice.
The Gaps That Undermine the Science
Early-phase trials remain male-dominated. Women represent just 29–34% of participants in phase I industry-sponsored studies, the very trials where safety and dosage are first evaluated.7
Sex-disaggregated data often isn’t analyzed or reported. Even when women are included in trials, outcomes are often generalized without accounting for key biological differences.8
Pregnant women remain largely excluded. Despite calls for inclusion and new guidance on ethical trial design, pregnant and lactating individuals are still widely excluded from most studies, leading to gaps in evidence-based care.9
Women experience more adverse drug reactions (ADRs). Studies have shown women are up to 1.7× more likely than men to experience ADRs, yet drug safety profiles are still often based on male-centric data.10
A clear example? In 2013, the FDA cut the recommended dosage of Ambien for women in half after discovering they metabolized the drug more slowly, increasing risk of next-morning impairment and accidents. That change came 20 years after the drug hit the market.11
And it’s not just about gender, intersectionality matters. Race, income, disability, geography, and age all shape clinical outcomes. If our trials don’t reflect that, our science doesn’t either.
This Isn’t Just Ethics… It’s ROI
Let’s talk dollars. According to the WHAM (Women’s Health Access Matters) initiative, doubling the NIH’s $350 million investment in women’s health research would yield a $14 billion return in just three years, thanks to improved outcomes, reduced burden of disease, and smarter, targeted therapies.12
And the women’s health market itself? It’s expected to exceed $60 billion by 2027, with growth driven by innovations in hormone health, diagnostics, chronic disease management, and digital care.2
Inclusive trials aren’t just better science, they’re better business.
Here’s What Real Progress Looks Like
If you're serious about building clinical programs that are ethical, effective, and future-ready, here’s where to start:
Design trials that disaggregate by sex from day one. Don’t wait for post-hoc analysis to uncover key differences, bake it into your protocol from the start.
Include pregnant and lactating women, ethically and responsibly. Updated FDA guidance and frameworks now support safe inclusion of these groups.6
Use AI to identify bias and close representation gaps early. Predictive tools can help spot disparities in recruitment or retention before they compromise your trial.
Prioritize women’s conditions as core research areas. Autoimmune disorders, cardiovascular disease, endometriosis, and migraine; these aren’t niche concerns. They’re large, underserved opportunities.
Incentivize transparency. From study design to publication, reward sex-based analysis, diverse cohort inclusion, and clear data reporting.
And maybe most importantly: Ask better questions. Don’t just ask, “Does this work?” Ask, “Who does it work for?”
Leading Isn’t Optional Anymore
We’re not in the awareness phase. We’re in the accountability phase. The evidence is overwhelming. The economic upside is undeniable. The policies are in place.
So the only question is: who’s going to lead?
Because this isn’t just a women’s issue.
It’s a science issue.
A safety issue.
A business issue.
An everyone issue.
And if you're not building with that in mind? You're already behind.
References
“NIH Revitalization Act Overview.” Office of Research on Women’s Health. 1993.
Women’s Healthcare Market Size Forecast. PR Newswire / Valuates Reports. 2022.
Inclusion of Women in Clinical Research. NIH Data Book. 2023.
SABV Policy Overview. NIH Office of Research on Women’s Health. 2020.
“Women’s Health Initiative Overview.” Women’s Health Initiative. Accessed 30 May 30.
Inclusion of Pregnant and Lactating Populations. U.S. Food and Drug Administration.
Fultinavičiūtė, Urtė. “Underrepresentation of Women in Early-Stage Trials.” Clinical Trials Arena.17 Oct. 2022.
Balch, Bridget. “Why We Know So Little About Women’s Health.” Association of American Medical Colleges. 26 Mar. 2024.
Gregory, Andrew. “‘Concerning’ lack of female-only medical trials in UK, say health experts.” The Guardian. 7 May 2025.
Benjeaa, Younes and Yves Geysels. “Gender Bias in the Clinical Evaluation of Drugs.” Applied Clinical Trials. 13 Aug. 2020.
“FDA Cuts Recommended Ambien Dose for Women.” NPR Health News. 2013.
Mickle, Kelly. “Carolee Lee: Demanding more for women." Time. 2 May 2024.