The Gender Gap in Medical Research
How Women's Health & Female Fertility Have Been Overlooked
For too long, medicine treated women as "little men."
That’s not a catchphrase—it’s an actual mindset that shaped generations of women’s health research.
Women’s bodies were considered secondary or too "complicated," and as a result, most of our health guidance, drug dosages, and even fertility care for women were based on male biology.
The impact? Profound.
Generations of women were left with incomplete answers about their health, often leading to fertility diagnosis delays, ineffective treatments, and missed opportunities for early intervention—especially when it comes to fertility.
Let’s explore why women are left out of medical research, what’s changed, and how you can use this knowledge to empower your own fertility journey.
Why Women Were Left Out of Medical Research
In the wake of the thalidomide tragedy of the 1960s—when a drug given to pregnant women for morning sickness caused severe birth defects in over 10,000 babies worldwide—researchers and regulators became deeply cautious about including women in clinical trials. [1]
By 1977, the FDA formally advised excluding women "of childbearing potential" from early-stage research. This blanket policy effectively sidelined nearly all women from drug development for over 15 years. [2] Scientists worried that hormonal fluctuations and reproductive complexities would "confound" results or increase liability.
But in protecting women from potential risks, the medical field inadvertently excluded them from potential benefits.
This exclusion has had serious consequences, as many medications and treatments have been developed and tested only on men, leading to a lack of understanding of how these treatments may affect women differently.
How This Set Fertility Research Back Decades
Because women were excluded from trials, early reproductive research largely focused on male fertility factors like sperm count and motility. [3] Critical female conditions such as polycystic ovary syndrome (PCOS) and endometriosis were underfunded, misunderstood, and underdiagnosed.
Take PCOS: today, we know it’s the leading cause of lower fertility in women, affecting about 6–13% of women globally. [4] Yet, it took decades for this to be fully recognized in clinical practice. Endometriosis tells a similar story—affecting around 10% of women of reproductive age, but with an average diagnostic delay of 7 to 10 years. [5]
Without inclusive research, we also missed essential insights into other fertility blockers like thyroid dysfunction, which can quietly sabotage hormone balance and fertility intentions without clear symptoms.
The consequences weren’t limited to diagnoses. Treatments were delayed, options were limited, and for too many women, the root causes of infertility remained a mystery.
What Changed: The Turning Point for Women’s Health Research
In 1993, everything began to shift.
The NIH Revitalization Act of 1993 made it mandatory to include women in federally funded clinical research. Around the same time, the NIH established the Office of Research on Women’s Health, whose mission is to ensure that women’s reproductive health care becomes an integrated part of medical science—not an afterthought.
Since then, we’ve made major progress:
- We now understand that ovarian reserve, the number of eggs a woman has, varies dramatically and declines earlier than once thought.
- Research has uncovered how autoimmune conditions, which disproportionately affect women, can directly impair fertility. [6]
- Studies confirm that environmental toxins, including endocrine-disrupting chemicals, interfere with hormonal function and reproductive health.
Perhaps most excitingly, scientists are finally investigating not just how to treat disease, but how to optimize fertility and hormone balance throughout a woman’s life.
The Gap That Still Remains
Despite the progress, women are still not fully represented in medical research today.
As of 2019, women made up only about 40% of participants in clinical trials for major diseases that affect them, including cardiovascular disease, cancer, and psychiatric conditions—far below their representation in the population. [1] And for women of color, the gap is even wider.
Many clinical trials fail to report or analyze data at the intersection of gender and race, leaving critical questions unanswered. [1]
This ongoing underrepresentation matters deeply for fertility, too.
Research into conditions like endometriosis, PCOS, autoimmune diseases, and “unexplained infertility” still lags behind, with limited funding and fewer studies focused on understanding root causes. And for women trying to conceive, this means many questions about hormone regulation, egg quality, environmental exposures, and immune factors remain frustratingly open-ended.
The good news? Awareness is growing. Researchers, policymakers, and advocacy groups are pushing for change, recognizing that true progress requires not just including women in studies, but designing research that addresses their specific health experiences from the ground up.
Global Fertility Trends: What Other Countries Teach Us
The United States isn’t alone in facing fertility challenges. But there are countries we can look to for inspiration—places that have invested in women’s health, research, and family-friendly policies with encouraging results.
Take France, for example. With a fertility rate around 1.8 (meaning 1.8 children per woman), France consistently outperforms the U.S. thanks to comprehensive women’s healthcare, widespread access to contraception and fertility treatments, subsidized childcare, and generous parental leave policies that support women throughout their reproductive years. [7, 8] The French government also actively promotes fertility awareness and reproductive education, making it easier for women to make informed decisions about their reproductive health.
In comparison, the U.S. fertility rate fell to 1.62 in 2023—well below the replacement level of 2.1 needed to maintain population stability. [9] Unlike France, the U.S. lacks universal access to fertility care and has fewer systemic supports that ease the balance of career and family life, which can discourage family-building.
This shows us that when women’s health is prioritized—not just in theory, but in practice—fertility outcomes improve. It’s a reminder that progress is possible when we study women properly, listen to their needs, and invest in systems that support them at every stage of life.
Wide Lab Ranges & Missed Diagnoses
Even with progress, many women today still face outdated clinical standards. Most lab reference ranges are based on data collected predominantly from men—or generalized populations that overlook women’s unique physiology. [10]
For example:
- Thyroid dysfunction can disrupt ovulation, yet many "normal" lab ranges miss subtle shifts that significantly impact fertility. [11]
- Vitamin D, crucial for hormone production and egg quality, is often under-tested or dismissed, despite studies showing clear links to reproductive success. [15]
This is where functional fertility care shines. We don’t settle for "normal"—we aim for optimal. By digging deeper into both female lab markers and those of their male partners, nutrient deficiencies, and hormone imbalances, we uncover what conventional medicine often overlooks.
POI Diagnosis & Testing
Early diagnosis of POI is essential to managing both fertility and long-term health. Your healthcare provider may start with a physical exam and pelvic exam, then order tests to evaluate:
- FSH levels which show how hard your brain is working to stimulate the ovaries. When FSH is high, it means your body is trying to get the ovaries to respond—but they aren’t producing enough hormones in return.
- Estrogen levels, including estradiol, a key hormone made by the ovaries that supports your menstrual cycle, bone health, and vaginal tissue. Low estradiol can indicate that the ovaries are no longer making enough estrogen.
- Luteinizing hormone (LH) and anti-Müllerian hormone (AMH). LH helps trigger ovulation, while AMH gives a snapshot of how many eggs (or follicles) remain in the ovaries. Low AMH suggests a diminished ovarian reserve.
- Genetic testing to identify any potential genetic causes that could be causing premature ovarian insufficiency.
- Autoimmune panels to detect underlying health conditions where the immune system may be attacking ovarian tissue.
An ultrasound may also be used to examine the ovaries and count ovarian follicles, giving a picture of ovarian reserve.
Conclusion
If you’ve ever felt dismissed, rushed through appointments, or told your labs look "fine" while you’re still struggling to conceive—there is a better path.
Functional fertility care bridges the gap between research and real life. It recognizes that your body is complex, interconnected, and worthy of personalized attention.
By focusing on root causes—like inflammation, nutrient deficiencies, hormonal imbalances, or hidden conditions such as PCOS or endometriosis—you can reclaim your path to pregnancy.
The science is catching up. And so can your care.
If you’re ready to understand your fertility at a deeper level, we invite you to explore our free masterclass. You’ll discover how we help women like you uncover hidden obstacles, optimize their health, and rewrite their fertility stories.
References
- [1] Balch, B. (2024, March 26). Why we know so little about women’s health. AAMC. https://www.aamc.org/news/why-we-know-so-little-about-women-s-health
[2] History of women’s participation in clinical research. (2024, April 24). https://orwh.od.nih.gov/toolkit/recruitment/history
[3] Turner, K. A., Rambhatla, A., Schon, S., Agarwal, A., Krawetz, S. A., Dupree, J. M., & Avidor-Reiss, T. (2020). Male Infertility is a Women’s Health Issue—Research and Clinical Evaluation of Male Infertility Is Needed. Cells, 9(4), 990. https://doi.org/10.3390/cells9040990
[4] World Health Organization: WHO & World Health Organization: WHO. (2025, February 7). Polycystic ovary syndrome. https://www.who.int/news-room/fact-sheets/detail/polycystic-ovary-syndrome
[5] Endometriosis. (2024, March 11). Yale Medicine. https://www.yalemedicine.org/conditions/endometriosis
[6] Understanding sex differences in autoimmune disease. (2024, February 27). National Institutes of Health (NIH). https://www.nih.gov/news-events/nih-research-matters/understanding-sex-differences-autoimmune-disease
[7] OECD Family Database. (2023). Family-friendly policies and fertility rates. https://www.oecd.org/els/family/database.htm
[8] Toulemon, L., Pailhé, A., & Rossier, C. (2008). France: High and stable fertility. Demographic Research, 19, 503–556. https://doi.org/10.4054/DemRes.2008.19.16
[9] Driscoll, A. K., & Hamilton, B. (2025). Effects of age-specific fertility trends on overall fertility trends: United States, 1990–2023. https://doi.org/10.15620/cdc/174576
[10] Merone, L., Tsey, K., Russell, D., & Nagle, C. (2022). Sex Inequalities in Medical Research: A Systematic Scoping Review of the literature. Women S Health Reports, 3(1), 49–59. https://doi.org/10.1089/whr.2021.0083
[11] Joshi, J. S., Shanoo, A., Patel, N., & Gupta, A. (2024). From Conception to Delivery: A Comprehensive review of Thyroid Disorders and Their Far-Reaching Impact on Feto-Maternal Health. Cureus. https://doi.org/10.7759/cureus.53362
[12] Dragomir, R. E., Toader, O. D., Mutu, D. E. G., & Stănculescu, R. V. (2024). The Key Role of Vitamin D in Female Reproductive Health: A Narrative review. Cureus. https://doi.org/10.7759/cureus.65560