While conversations about the gender pay gap have taken center stage, there’s another, less visible gap with serious consequences—the gender health gap. For decades, women have been underrepresented in clinical research and medical studies, leading to a healthcare system that has often failed to account for female biology. This discrepancy has resulted in misdiagnoses, ineffective treatments, and compromised care for millions of women. But what caused this gap, and why is closing it so critical not only for health but also for economic reasons?

A Short History of Misrepresentation

The exclusion of women from medical research is not new. For much of the 20th century, women were routinely left out of clinical trials, even those related to major health issues like heart disease. For instance, the Baltimore Longitudinal Study of Aging, which began in 1958, did not enrol any women for its first 20 years. Similarly, the Physicians’ Health Study, which concluded that aspirin reduces the risk of heart disease, involved over 22,000 men and zero women. Another example is the 1982 Multiple Risk Factor Intervention Trial (MRFIT), which studied 13,000 men to evaluate heart disease prevention but did not include a single woman. Even trials focused on conditions affecting women, such as a hormone replacement therapy study in the 1960s, enrolled over 8,300 men and no women.

Female exclusion in research extends even to animal studies. A 2010 review by Annaliese Beery and Irving Zucker found that male bias in preclinical research, particularly in neuroscience, was prevalent, with studies on male animals outnumbering those on females by 5.5 to 1. According to Maya Dusenbery in her book Doing Harm: The Truth About How Bad Medicine and Lazy Science Leave Women Dismissed, Misdiagnosed, and Sick, this bias has deep historical roots, leading to a healthcare framework that inadequately serves women's needs.

Why Has This Happened?

Several factors have contributed to this imbalance. Maya Dusenbery highlights that the historical landscape of medicine has been dominated by men, who have overwhelmingly filled roles as doctors and researchers. This male-centric framework has influenced the focus of medical studies and clinical trials, which largely prioritize the male body and male experiences.

Furthermore, a significant concern has been the financial and legal risks associated with women of childbearing age participating in trials, particularly the possibility of pregnancy during a study. Fears about harming a developing foetus have led to the systematic exclusion of women from drug trials. Additionally, recruiting women is often seen as more complex and costly for trial sponsors. Female subjects may be more likely to experience adverse drug reactions, and biological differences such as hormonal fluctuations and age-related changes create additional subpopulations that require specific analysis. From an economic perspective, this has been seen as costly and burdensome, leading to a prioritization of male participants.

Consequences of the Gender Health Gap

The underrepresentation of women in clinical research has significant and far-reaching health consequences. For example, cardiovascular disease is the leading cause of death in both men and women, but research often focuses on male patterns of the disease, leaving many women undiagnosed or misdiagnosed. Women often experience different symptoms, such as fatigue or nausea, rather than the classic male symptom of chest pain; yet treatment protocols largely cater to men.

These disparities are not only dangerous from a health perspective but also contribute to higher healthcare costs. According to a report by Deloitte, the economic case for a more women-centric healthcare system is clear: addressing women’s health needs could significantly reduce overall healthcare costs. A system designed with women’s biology and medical needs in mind could improve outcomes, lower hospital readmission rates, and decrease the prevalence of chronic conditions like heart disease and osteoporosis.

A 2024 report by Cure Biotech titled The State of Women’s Health in 2024 reveals that women's health companies receive just 2 percent of venture funding allocated for the entire healthcare industry, despite women using more healthcare services than men, utilizing preventative services at a higher rate, and controlling 80 percent of healthcare spending decisions. This highlights the market perception that women’s health treatments and therapies do not represent a mature enough market for investors.

A Shift Toward Equity

Fortunately, change is underway, albeit slowly. In 1993, the National Institutes of Health (NIH) Revitalization Act mandated the inclusion of women in clinical trials. This marked a turning point, but it wasn’t until 2015 that the NIH implemented a policy requiring researchers to consider sex as a biological variable (SABV) in their studies, necessitating a strong justification to include only one sex. Additionally, in 2016, the NIH began mandating that research involving animals must include both male and female subjects to ensure sex equity in preclinical trials.

Yet, there’s still much room for progress. A recent study found that women still make up only 29–34% of participants in early-phase industry-sponsored clinical trials, and their participation is low in areas like gout disease drug testing, where women constitute only 5.3% of participants, despite representing 30% of the population affected by the disease.

Importantly, in 2019, Kannan and colleagues explored recruitment bias in a cross-sectional study of patients volunteering for research through an online portal. Their findings revealed that the underrepresentation of women in clinical trials is not due to a lack of willingness to participate but rather to bias within trial design and recruitment strategies. This highlights the need for a comprehensive re-evaluation of how trials are structured and who they are designed to include.

The Society for Women’s Health Research (SWHR), founded in the 1980s, continues to play a pivotal role in advocating for these changes. In 2021, SWHR launched its Women’s Health Equity Initiative, aimed at raising awareness and educating policymakers about disparities in women’s healthcare access and outcomes.

The Importance of Closing the Gender Health Gap

Addressing this gap is not just a matter of fairness; it’s crucial for improving health outcomes and reducing healthcare costs. By including women in clinical research, we can develop more effective treatments and preventative measures, reducing the need for prolonged and repeated care. This, in turn, can lessen the financial burden on healthcare systems and lower the cost of treating conditions that disproportionately affect women.

From an economic perspective, investing in women’s health research presents substantial business opportunities. The women’s health market represents a growing sector with the potential for significant returns. Companies that prioritize female-centric medical research stand to benefit from untapped markets, while governments can save on healthcare costs by reducing preventable and poorly treated conditions in women.

Conclusion

The gender health gap reflects a legacy of bias in clinical research that continues to have serious consequences for women’s health. Although progress has been made in recent years, much work remains to ensure equitable representation in both human and animal studies. Achieving sex equity in medical research will not only improve health outcomes for women but also reduce healthcare costs and create new opportunities for innovation in the healthcare market. The push for change is gaining momentum, but it’s clear that addressing this gap is essential for creating a more just and effective healthcare system for everyone.