The landscape of clinical trials is undergoing a radical transformation. Driven by technological innovation and a growing demand for inclusivity, researchers and pharmaceutical companies are rethinking the design and execution of clinical trials. One critical area that has long been overlooked -but is now gaining attention- is hormonal health. For decades, clinical trials have prioritized a one-size-fits-all approach, intentionally neglecting demographic factors such as the nuanced and dynamic role of hormonal fluctuations, particularly in women and gender-diverse populations. Today, experts recognize the menstrual cycle as a "fifth vital sign," an essential health indicator as important as blood pressure, temperature, heart rate, and respiratory rate.
Despite this acknowledgment, most clinical trials still fail to systematically incorporate menstrual and hormonal health data, often limiting evaluation to pregnancy tests for participant eligibility. This exclusion has led to incomplete datasets and treatments that are less effective or even harmful for those with female physiology or hormone-sensitive conditions. The failure to integrate this critical data into clinical research represents a significant gap in our understanding of health outcomes for half the population.
Clinical trial methodologies have been plagued by an inability to collect and account for diverse and representative data. For much of modern medical history, cisgender men have been the default participants in biomedical research, largely to avoid the “complexities” of female hormonal cycles. This exclusion has led to a scientific record predominantly composed of incomplete data sets (also known as the sex and gender data gap) that has led to increased misdiagnoses as well as protocols, treatments, and best practices that are less effective -or even harmful- for those with female physiology or hormone-sensitive conditions.
The lack of sex-specific data in clinical research has led to medications and treatments that are less safe and effective for women. Women experience nearly twice the rate of adverse drug reactions compared to men, largely due to dosing guidelines historically developed from male-dominated trials. A meta-analysis of 86 medications found significantly higher active drug concentrations in women’s blood than men’s, causing disproportionately higher adverse reactions. A notable example is zolpidem (Ambien), a sleep medication approved in 1992 at standard dosages. It took two decades for regulators to recognize women metabolized the drug more slowly, increasing the risk of next-day impairment, prompting the FDA in 2013 to halve the recommended dose for women. Furthermore, between 1997 and 2001, eight of the ten drugs withdrawn from the U.S. market posed greater health risks to women, highlighting systemic failures in anticipating sex-specific safety profiles.
Today, we can clearly see the impacts of not collecting or analyzing this data in retrospect. We now know based upon these real-world examples and a number of peer reviewed studies that hormonal variability influences everything from drug metabolism to immune response and psychological health. Ignoring these variables isn't just an oversight; it’s a scientific limitation that compromises the validity of trial results and, quite frankly, health outcomes globally. Here are just a few additional examples:
A critical source of female-specific variability is the menstrual cycle and its hormonal fluctuations, which influence drug metabolism, immune responses, and overall health. Hormones modulate liver enzymes affecting medication absorption and clearance, and fluctuations in estrogen and progesterone impact vascular function, inflammation, and brain chemistry. Menstrual health is a vital sign of overall health. Changes in cycle regularity or symptoms can be early indicators of stress, thyroid disorders, polycystic ovary syndrome (PCOS), and other conditions. Incorporating this information into trials could improve precision, clarify why therapies perform differently across cycle phases, and identify hormone-related side effects. Ignoring menstrual cycles omits a significant piece of the biological puzzle in women’s health.
Fortunately, we now live in an era of technological progress capable of dismantling these barriers and blind spots. Digital health tracking means millions of women already collect menstrual data via smartphone apps, wearable sensors, and home-based hormone monitors. Period-tracking apps like Clue have become ubiquitous, empowering women to log cycles, symptoms, and moods. As of 2021, over 50 million women worldwide were using apps for menstrual tracking. Wearables such as smartwatches, health rings and now even earrings (Oura, Garmin, Apple, Incora Health) can capture changes in heart rate, body temperature, and sleep patterns correlating with menstrual phases.
User-friendly kits for measuring hormones like estrogen and progesterone through home samples from Eli Health and machine-learning algorithms that analyze symptom diaries are further simplifying data collection. Remote clinical trial platforms enable easier recruitment and follow-up of participants across menstrual cycles without excessive clinic visits. These innovations eliminate past excuses about complexity, making it feasible to design trials inclusive of menstrual data without ballooning costs or timelines. By embracing rather than avoiding hormonal variability, we can improve trial precision, proactively identify sex-specific adverse effects, and reduce unexplained outcome variability and trial failures.
Capturing hormonal health data isn’t just about inclusion—it’s about scientific precision. By incorporating menstrual cycle data, hormonal fluctuations, and endocrine profiles, researchers can:
To make this happen, here are just few ways that together GSD Health Research and My Normative are contributing to closing the sex and gender data gap and our economy:
Integrating menstrual and hormonal data into clinical trials represents both an ethical imperative and a scientific opportunity. It ensures that women are not merely included but fully considered in research. Routine collection of menstrual data should become standard practice, enhancing our ability to identify sex-specific health outcomes and optimize therapeutic interventions. Ultimately, a more inclusive research paradigm will benefit everyone, driving treatments that reflect true biological diversity and equity. Treating menstrual health as a critical vital sign enables a future where medical research genuinely reflects the health needs of all individuals.
The future of health innovation depends on our ability to recognize and integrate the full spectrum of human health — including hormonal health. By normalizing the inclusion of hormonal data, we not only advance science, we also take a vital step toward healthcare equity.
Recognizing the urgent need for transformative, participant-centered research, GSD Health Research and My Normative have partnered to advance the integration of hormonal and menstrual health data into clinical trials. By combining GSD’s expertise in inclusive, digitally-enabled clinical research and My Normative’s robust platform for capturing menstrual and hormonal data, this partnership aims to ensure that hormonal health becomes foundational—not optional—in research, ultimately driving forward equitable health outcomes for women and gender-diverse populations globally.
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This article was co-developed by contributors from GSD Health Research and My Normative — two organizations working to embed hormonal and menstrual cycle data into modern clinical research and improve equity and precision in trial design.
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