DNA helix intertwining gender symbols representing equality in medical research.

Clinical Trials: Are Women Equally Represented?

Rhea Morgan in Health & Wellness December 2025 • 4 min read.

"Uncovering Sex Bias in Medical Research and Why It Matters for Healthcare Equity"

For years, it's been an accepted truth that clinical trials, the bedrock of medical advancement, have often been skewed towards male participants. This isn't just a matter of fairness; it's a critical issue that impacts the effectiveness and safety of medical treatments for everyone. The historical underrepresentation of women in these trials has led to a situation where medical knowledge and practices are, in many ways, based on a male standard.

The implications are far-reaching. Because men and women can respond differently to medications and treatments due to physiological differences, a lack of female participation can result in inaccurate dosage guidelines, increased side effects, and even ineffective therapies for women. This gap in research not only perpetuates health inequities but also undermines the quality of care that women receive.

Now, a new study is shedding light on whether this sex bias continues to persist in contemporary clinical trials. By examining a large dataset of interventional trials, researchers are providing crucial insights into the current state of gender representation in medical research. The findings are a call to action, urging the medical community, policymakers, and funding bodies to prioritize inclusivity and address the systemic biases that continue to affect women's health.

The Numbers Don't Lie: Unveiling Sex Disparities in Clinical Trials

DNA helix intertwining gender symbols representing equality in medical research.

A comprehensive analysis of data extracted from ClinicalTrials.gov has revealed some concerning trends in the representation of women in clinical trials. The study focused on interventional Phase I, II, and III clinical trials with adult subjects, spanning from January 1, 2011, to December 31, 2013. Researchers meticulously examined the number and sex of participants, funding sources, and other key factors to determine the extent of sex bias.

Out of the 1,501 studies scrutinized, a total of 177,656 male subjects (51.1%) and 170,331 female subjects (49.0%) were included. While the overall numbers appear relatively balanced, a closer look reveals significant disparities across different phases of clinical trials.

Phase I Trials: Showed a significant male bias, with 64.1% male participants compared to only 35.9% female participants.
Phase II Trials: Displayed a more balanced representation, with 48.4% male and 51.6% female participants.
Phase III Trials: Also exhibited a near-equal distribution, with 51.0% male and 49.1% female participants.

Funding sources also played a role in sex representation. NIH-funded trials, for example, included 56.6% male and 43.4% female participants, while industry-funded trials showed a slightly better balance with 50.7% male and 49.3% female participants. These findings underscore the complex interplay of factors that contribute to sex bias in clinical trials and highlight the need for targeted interventions to address these disparities.

The Path Forward: Ensuring Equitable Representation in Clinical Trials

The study's findings serve as a crucial reminder of the persistent sex bias in clinical trials and the urgent need for change. While progress has been made in recent years, significant disparities remain, particularly in early-phase trials and among certain funding sources. By acknowledging these biases and implementing targeted strategies, the medical community can ensure that clinical research truly reflects the diversity of the population it serves, leading to more effective and equitable healthcare outcomes for all.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1089/jwh.2017.6873, Alternate LINK

Title: Sex Bias In Interventional Clinical Trials

Subject: General Medicine

Journal: Journal of Women's Health

Publisher: Mary Ann Liebert Inc

Authors: Vivek S. Prakash, Neel A. Mansukhani, Irene B. Helenowski, Teresa K. Woodruff, Melina R. Kibbe

Published: 2018-11-01

Everything You Need To Know

Why are clinical trials so important, and what's their connection to sex representation?

Clinical trials are essential for medical advancements. They involve testing new treatments or interventions on human participants. The article highlights that these trials have historically underrepresented women. The significance lies in the potential for medical knowledge to be skewed towards a male standard, leading to inaccurate treatment guidelines for women. This has implications for healthcare outcomes because men and women can respond differently to medications due to physiological differences, a lack of female participation can result in inaccurate dosage guidelines, increased side effects, and even ineffective therapies for women.

What is sex bias in clinical trials, and what does the study reveal about it?

Sex bias in the context of clinical trials refers to the unequal representation of men and women in these studies. The article reveals that such biases have persisted. The study analyzed data from ClinicalTrials.gov, revealing significant disparities in the representation of women across different phases of clinical trials. For instance, Phase I trials showed a significant male bias. The implications of sex bias are severe, potentially leading to healthcare inequities and undermining the quality of care for women. Inaccurate dosage guidelines, increased side effects, and even ineffective therapies for women.

Why are the study's findings so important?

The study's findings are crucial because they highlight the persistent sex bias in clinical trials. The research examined a large dataset of interventional Phase I, II, and III clinical trials. The study underscores the need for change, particularly in early-phase trials and among certain funding sources. The significance lies in the call to action for the medical community, policymakers, and funding bodies to prioritize inclusivity. Addressing these biases can lead to more effective and equitable healthcare outcomes for all.

What was the scope of the study, including the time frame?

The study examined clinical trials from January 1, 2011, to December 31, 2013, using data from ClinicalTrials.gov. It focused on interventional Phase I, II, and III clinical trials with adult subjects. Researchers scrutinized the number and sex of participants, funding sources, and other key factors. The significance of this timeframe is to provide crucial insights into the current state of gender representation in medical research. The implications include providing up-to-date evidence of sex bias in trials.

What were the key findings related to the different phases of clinical trials?

The findings related to the different phases of clinical trials revealed varying degrees of sex representation. Phase I trials showed a significant male bias. Phase II trials displayed a more balanced representation. Phase III trials also exhibited a near-equal distribution. These disparities across different phases of clinical trials highlight the need for targeted interventions to address these issues. It underscores the complex interplay of factors that contribute to sex bias in clinical trials. It indicates that progress in achieving equitable representation varies across different stages of research.