The Short Read
- The gender gap in medicine trials refers to the historical and ongoing underrepresentation of women, female animals, and sex-specific analyses in medical research.
- For decades, many studies preferred male participants or male animals because female hormonal cycles were seen as too complex.
- That shortcut created a long-term evidence gap.
- Women can experience diseases differently, respond to drugs differently and report different symptoms.
- When studies do not include enough women or fail to analyse results by sex, doctors may miss important differences in safety, dosage and treatment response.
- Precision medicine needs better evidence for women, not simply better technology.
- The way forward is to include women across trial stages, study female animals and cells, report results by sex, fund women’s health research, and design trials that reflect real life.
Gender gap in trials and the problem hiding inside “standard medicine”
Let us face an uncomfortable truth. A lot of modern medicine still carries the shadow of an old research habit: study the male body first, then assume the findings will broadly apply to everyone else.
That assumption was convenient. It was not harmless.
The gender gap in medicine trials has shaped what scientists know, what doctors are taught, what drug labels say, what symptoms are recognised and how women are treated when they walk into clinics with pain, fatigue, heart symptoms, autoimmune conditions, mental health concerns or reactions to medicines.
None of it says that women are medically mysterious. It is about saying women are biological human beings, not footnotes.
Sex can influence cells, hormones, immune responses, metabolism, disease risk and treatment response. Gender can also affect exposure, access to care, stress, symptom reporting, diagnosis, and treatment. Together, they shape health in ways that research cannot afford to ignore.
Yet for decades, researchers have been leaving out women in early-stage studies. They have been avoiding female animals in lab research. Researchers worried that hormonal cycles would complicate the data. Pregnant women were excluded for safety reasons, often without creating better ways to study pregnancy safely. Men became the easier default.
The result is a knowledge base that looks more neutral than it is. When evidence is built unevenly, healthcare becomes uneven too.
Gender gap in medicine trials: Why were women left out?
The usual explanation sounds scientific at first.
Researchers always consider female hormonal cycles as variable. They worry that including women would make studies messier, more expensive or harder to interpret. In drug trials, there were also fears around pregnancy and potential harm to a foetus. In basic science, researchers often preferred male animals because they were seen as simpler research models.
But “simpler” is not the same as better.
If a medicine has to work in women’s bodies, then we cannot treat women’s biology as a complication. It is part of the science.
A study that avoids female biology because it is complex may produce cleaner data, but less useful medicine. Real patients have hormones. Real patients have menstrual cycles, menopause, pregnancy history, contraceptive use, body composition differences, immune differences and different patterns of disease.
Medicine cannot call itself precise if it studies a simplified version of humanity.
That is why the recent Science Advances paper is important. It argues that precision medicine needs an evidence base that reflects women’s biology. That means changing how research is funded, designed, analysed and reported.
In plain English, we must not add women at the end of medical knowledge. They should be a part of the research from the beginning.
Change in Content has earlier covered the underrepresentation of women in drug trials. This newer conversation goes further. It asks whether medicine can become truly modern without correcting the older bias in its evidence base.
What happens when the evidence is incomplete?
The consequences are not abstract.
If researchers do not study women properly, symptoms may be misunderstood. Drug doses may be less accurate. Side effects may be missed. Diagnostic tools may work better for men than women. Disease risk may be estimated poorly. Doctors may rely on evidence that does not fully reflect the patient in front of them.
Take adverse drug reactions.
A US government review found that 8 out of 10 prescription drugs withdrawn from the market between 1997 and 2000 posed greater health risks for women than men. That does not mean every drug is unsafe for women. It means drug safety can look different when women’s outcomes are properly examined.
That is the kind of finding that should have changed the research culture faster than it did.
The issue also shows up in everyday healthcare. Women are often told symptoms are stress, anxiety, hormones or “normal”, especially when doctors do not have enough sex-specific evidence to recognise disease patterns. Change in Content has written about women and illness in organisations because the same problem follows women into workplaces, too. If women’s health is poorly understood, their pain is often treated as an inconvenience.
Research gaps become clinical gaps. Clinical gaps become trust gaps. And trust gaps make women delay care, doubt themselves or accept poor treatment.
The “include women” answer is not enough
At first glance, the solution seems obvious: include more women in trials. Yes, that matters. But it is only step one.
A trial can include women and still fail women if the results are not analysed by sex. If researchers combine all results and report only an average, important differences can disappear. The average patient may not exist in real life.
The better question is not only “were women included?”
It is also:
- Were enough women included to detect meaningful differences?
- Were women included in early-stage trials, not only late-stage ones?
- Were pregnant and breastfeeding women considered, where ethically and scientifically possible?
- Were female animals used in preclinical studies?
- Were the results analysed separately by sex?
- Were hormone status, age, pregnancy, menopause or contraceptive use recorded where relevant?
- Were women’s health conditions funded properly?
- Were adverse effects reported by sex?
- Did the final paper tell doctors what changed for women?
That is why sex-disaggregated reporting matters.
If a study includes women but hides the difference in a combined average, the evidence still fails the people it claims to represent.
Precision medicine cannot ignore half the population
Precision medicine promises treatment tailored to the individual. It discusses genes, biomarkers, lifestyle, environment, and risk profiles. That sounds like the future.
But there is a basic problem. Precision medicine cannot be precise if it is built on imprecise evidence about women.
A genetic test, drug dose, cancer treatment, heart-risk model or mental health therapy may all behave differently across bodies and social realities. If the data behind those tools underrepresent women, especially women across different age groups, ethnicities, and life stages, the promise becomes uneven.
That is especially important as AI enters healthcare.
AI systems learn from existing data. If the data is biased, incomplete, or male-heavy, the model may reproduce the same blind spots more quickly and at scale. A machine can only be as fair as the evidence it is trained on and the questions its designers ask.
That is why women’s health research is not a niche topic. It is a future-of-medicine issue.
Better evidence for women helps doctors treat women better. It also improves science for everyone because it forces researchers to understand variation rather than pretend it is noise.
What researchers and funders must do
The reform list is not mysterious.
- Funding bodies should require serious sex-specific research plans. They should not treat women’s health as a side category that receives attention only during awareness months.
- Ethics committees should ask whether excluding women is scientifically justified.
- Journals should require authors to report sex composition clearly and analyse results by sex where relevant.
- Preclinical studies should include female animals and cells unless there is a strong reason not to.
- Clinical trials should recruit women across life stages, including older women, where appropriate.
- Researchers should design studies around real patients, not idealised bodies.
- Drug regulators should look closely at sex differences in safety, dosage and adverse reactions.
- Medical education should teach sex and gender differences as mainstream science, not extra reading.
- Hospitals should collect better sex-disaggregated data from routine care.
- Patient groups should be involved early, especially for conditions that disproportionately affect women.
None of this is anti-science. It is better science.
What women can do as patients
The burden of fixing research does not sit with patients. But women can still use this knowledge in practical ways.
- Ask whether a medicine has different side effects in women.
- Ask whether dosage advice changes by body weight, age, pregnancy status, menopause, kidney function or other factors.
- Tell your doctor if symptoms change across the menstrual cycle, during pregnancy, the postpartum period, or menopause.
- Report side effects clearly. Do not minimise them.
- Ask if a test or treatment has been studied in women like you.
- Keep records of medication reactions.
- Seek a second opinion if symptoms are repeatedly dismissed.
- If eligible and comfortable, consider participating in well-regulated clinical research.
This is not about becoming suspicious of medicine. It is about becoming more informed inside it.
Women deserve healthcare that listens to them, studies them and treats them as full evidence-worthy patients.
Why this matters in India too
India cannot treat this as a distant Western research debate.
Indian women already face gaps in diagnosis, access, affordability, workplace support and health literacy. If the global evidence base itself has gender gaps, those gaps can become sharper in countries where women may also delay care because of family duties, cost, stigma or lack of control over health decisions.
Women’s health is still too often discussed only through reproduction. But women’s bodies do not exist only for fertility. Women need better evidence in cardiology, neurology, oncology, pain, autoimmune disease, mental health, infectious disease, metabolic health, ageing, occupational health and drug safety.
Change in Content has previously written about the lack of support for women’s health. The gender gap in medical trials shows why support must begin much earlier, inside laboratories, grant applications, trial protocols and medical journals.
If the research does not see women properly, the clinic may not either.
The cure begins with better questions
The gender gap in medicine trials is not a story of bad doctors or careless scientists alone. It is a story of a system that made male biology the shortcut and called it standard.
That shortcut has lasted too long. The hopeful part is that this can be fixed.
Research rules can change. Funding can change. Trial design can change. Journals can demand better reporting. Regulators can ask sharper questions. Medical colleges can teach differently. Patients can ask more informed questions. Health companies can build more inclusive data systems.
The future of medicine should not ask women to fit evidence that never fully studied them. It should build evidence that fits them, too.
Precision medicine will earn its name only when women’s biology is not treated as a complication, but as knowledge the world should have gathered long ago.
Editorial Note and Disclaimer
This article is a DEI Insights explainer inspired by the Science Advances paper “Precision medicine’s blind spot: Rebalancing the evidence base to reflect women’s health.” The paper argues that precision medicine requires stronger evidence that reflects women’s biology, including reforms in funding, study design, and sex-disaggregated reporting.
The article also draws on wider evidence that women and female animals have historically been underrepresented in biomedical research. The NIH Revitalisation Act of 1993 required NIH-funded clinical trials to include women and minorities, while NIH’s later sex-as-a-biological-variable policy expects sex to be factored into research design, analysis and reporting in vertebrate animal and human studies.
The clinical consequences are not theoretical. A US GAO review found that 8 of 10 prescription drugs withdrawn from the market between 1997 and 2000 posed greater health risks for women than men. Research roadmaps also stress that sex- and gender-disaggregated data is needed to identify illness distribution, risk exposure, service access and treatment outcomes more accurately.
Sources
Science Advances: Precision medicine’s blind spot: Rebalancing the evidence base to reflect women’s health
NIH policy on sex as a biological variable (NIH)
NIH inclusion policy for women and minorities in clinical research (Policy)
US GAO review on drugs withdrawn from the market and risks for women (GAO Review)
Roadmap for sex- and gender-disaggregated health research (PMC)
PLOS Medicine article on sex-disaggregated health data (PLOS)
