Study Reveals Critical Gap: Less Than 1% of US Clinical Trials Include Pregnant Participants
Key Insights
A comprehensive analysis of ClinicalTrials.gov (search) data shows that only 0.8% of 44,160 randomized controlled trials included pregnant participants, while 75% explicitly excluded them.
Industry-funded trials were significantly less likely to include pregnant participants, with only 23% of pregnancy-inclusive trials receiving industry funding compared to 77% of other trials.
Among the few trials including pregnant participants, 38% focused on labor/delivery, while only 19 trials addressed chronic conditions like anxiety (search), depression (search), and asthma (search), highlighting a critical evidence gap.
The landscape of clinical research continues to show significant gaps in addressing the medical needs of pregnant individuals, according to a new study published in the American Journal of Obstetrics and Gynecology (search). Analysis of data from ClinicalTrials.gov (search) over the past 15 years reveals that fewer than 1% of clinical trials enrolled pregnant participants, raising serious concerns about the evidence base for medical treatment during pregnancy.
Current State of Pregnancy-Related Clinical Trials
Of 44,160 randomized controlled trials (RCTs) analyzed, only 362 (0.8%) included pregnant participants. A striking 75% of trials actively excluded pregnant individuals, while 24% did not specify their inclusion or exclusion. The study reveals a stark contrast in trial characteristics between pregnancy-inclusive and exclusive studies.
Pregnancy-inclusive trials showed distinct patterns:
- 40% were open-label studies (compared to 30% in other trials)
- 34% focused on prevention methods (versus 5% in other trials)
- Only 23% received industry funding (compared to 77% of other trials)
Focus Areas and Research Gaps
Among the limited number of trials including pregnant participants:
- 136 trials (38%) focused on labor and delivery
- 80 trials (22%) studied pregnancy-related conditions
- 53 trials (15%) investigated preterm labor
- 57 trials (16%) addressed infectious diseases, primarily malaria and HIV
- Only 19 trials (5%) examined chronic conditions
- 9 trials (2%) studied pregnancy symptoms
"When pregnant women are excluded from drug trials, it is harder to know if the medication is safe for mothers and their children," explains Dr. Alyssa Bilinski, assistant professor at Brown University's School of Public Health. "This means that some people might decide to take medications even absent rigorous evidence, which could lead to harmful side effects."
Historical Context and Implications
The study highlights a concerning lack of progress despite increased awareness of the need for pregnancy-specific evidence. The FDA's requirement for pharmaceutical companies to demonstrate drug safety and efficacy wasn't established until 1962, and the mandate to include women in trials only came in 1993.
"We found only 19 trials for non-infectious chronic conditions like anxiety (search), depression (search) and asthma (search) that have included pregnant participants," notes Dr. Bilinski. "While it may seem risky to include pregnant people in research, it's even worse to leave them guessing based on incomplete information."
Impact on Healthcare Decision-Making
The limited inclusion of pregnant participants in clinical trials creates significant challenges for healthcare providers and patients. Without robust evidence from controlled trials, healthcare professionals must make treatment decisions with incomplete information about drug safety and efficacy during pregnancy. This knowledge gap can lead to either unnecessary avoidance of potentially beneficial treatments or use of medications without adequate safety data.
The findings underscore the urgent need for increased inclusion of pregnant participants in clinical research, particularly in studies of common chronic conditions that frequently affect pregnant individuals. This shift would help ensure that pregnant people receive evidence-based care supported by robust clinical data rather than relying on limited or extrapolated evidence.