Stunning Disparity: Only 1% of US Clinical Trials Include Pregnant Patients

A recent study conducted by Brown University researchers has raised concerns about the consistent exclusion of pregnant women from clinical drug trials, a practice that could have significant implications for both maternal and child health. Published in the American Journal of Obstetrics and Gynecology, the study analyzed over 90,000 drug trials conducted over the past 15 years, focusing on women of reproductive age. Alarmingly, only 0.8% of these trials included pregnant participants, while about 75% explicitly excluded them.

This lack of inclusion in clinical research is problematic because it leaves critical questions about the safety and efficacy of medications for pregnant women unanswered. According to Alyssa Bilinski, a health policy researcher at Brown University and one of the study's authors, this exclusion can hinder the use of potentially beneficial medications. Pregnant individuals and their healthcare providers may be reluctant to use drugs with limited safety data, which could delay the introduction of helpful treatments. On the other hand, when harmful side effects arise, they are more likely to be discovered after the medication has been used by many people, simply because not enough participants—particularly pregnant women—have been included in the trials.

The study found that while some trials included pregnant individuals, they primarily focused on conditions specific to pregnancy, such as preterm birth and nausea. In contrast, chronic health issues affecting pregnant women, like anxiety, depression, and asthma, were mostly overlooked. Bilinski noted that only 19 trials focused on non-pregnancy-related chronic conditions and included pregnant participants. This lack of comprehensive research on common health issues in pregnancy highlights the need for more inclusive studies.

Efforts have been made by organizations such as the National Academies of Science, Engineering, and Medicine, as well as the FDA, to encourage greater participation of pregnant people in clinical trials. These proposals include adjusting funding and timelines to accommodate the unique challenges of researching this population, improving communication to address liability concerns, and revising how pregnant individuals are categorized in some review processes.

Despite these efforts, the study revealed that the inclusion of pregnant participants in drug trials has not significantly improved over the past 15 years. The authors of the study, Bilinski and Natalia Emanuel, an economist at the Federal Reserve Bank of New York, argue that more randomized controlled trials (RCTs) need to include pregnant participants. They noted that it was only in 1993 that clinical trials were required to include women at all. Given this relatively recent history, Bilinski expressed hope that in 30 years, the lack of quality evidence on the safety of medications during pregnancy will seem as outdated as the previous exclusion of women from trials.

The historical context of these practices is also worth noting. The U.S. Food and Drug Administration (FDA) did not require pharmaceutical companies to demonstrate the safety and efficacy of their medications until 1962. Only in 1993 did guidelines mandate the inclusion of women in clinical trials, marking a significant shift, but not one that has yet fully addressed the gap in research regarding pregnant women.

The exclusion of pregnant women from clinical trials means that there is a significant gap in understanding how medications may impact maternal and fetal health. Pregnant women are often left to make healthcare decisions based on incomplete or outdated information, which can lead to either the use of unsafe medications or the avoidance of potentially helpful treatments due to uncertainty about their safety.

The study also found that 24% of the trials reviewed did not specify whether pregnant participants were included, but further investigation revealed that pregnant individuals were often excluded from these studies as well. Trials that did include pregnant participants generally focused on pregnancy-related conditions such as labor and the prevention of preterm birth, while other chronic conditions, such as asthma and diabetes, were largely ignored.

Bilinski and Emanuel's study highlights the need for reforms in how clinical trials are conducted. Randomized controlled trials, considered the gold standard for testing the safety and efficacy of drugs, rely on carefully selected groups of participants, some of whom receive treatment while others do not. However, by excluding a key group—pregnant women—the effectiveness of these trials is limited, leading to gaps in our understanding of medication safety during pregnancy.

The researchers used data from ClinicalTrials.gov, a comprehensive database of clinical trials, to underscore the importance of including pregnant women in these studies. Their work aims to raise awareness about the lack of representation of pregnant individuals in clinical research and to advocate for changes that will improve the quality of maternal health care.

As medical research continues to advance, it is crucial that pregnant individuals are included in clinical trials to ensure that drugs are safe for both mothers and their children. Bilinski and Emanuel hope that in the future, the absence of data on the safety of medications during pregnancy will be viewed as an outdated and unacceptable oversight. They envision a future in which pregnant people are routinely included in clinical trials, empowering them to make informed decisions about their health and well-being.

References:

1. American Journal of Obstetrics and Gynecology. "Inclusion of Pregnant Individuals in Clinical Trials: A Review of the Past 15 Years." American Journal of Obstetrics and Gynecology (2025). https://www.sciencedirect.com/science/article/abs/pii/S0002937825000031.

(Input from various sources)

(Rehash/Sai Sindhuja K/MSM)