Inclusion and participation of pregnant and breastfeeding women and people in non-obstetric clinical trials: a rapid scoping review
This rapid scoping review maps existing evidence on the inclusion and participation of pregnant and breastfeeding individuals in non-obstetric clinical trials, revealing low inclusion rates (0–14%) and identifying key themes such as risk, trust, and practical barriers that influence their engagement.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
For decades, a quiet but dangerous gap has existed in how we understand medicine for pregnant and breastfeeding people. When doctors prescribe treatments for common illnesses like infections or heart conditions, they rely on clinical trials—large, carefully controlled studies where new drugs or vaccines are tested on volunteers. These trials are the gold standard for knowing if a treatment is safe and effective. However, for a long time, the people running these studies have almost always excluded women who are pregnant or breastfeeding. The logic was simple and protective: because a developing fetus or a nursing baby is so vulnerable, researchers decided it was safer to keep them out of the experiment entirely. This approach was meant to shield the unborn from potential harm, but it created a different kind of danger. By keeping these people out of the data, the medical world is left guessing about how treatments work for them. Doctors are forced to prescribe medications without clear evidence of safety, and pregnant people are often denied treatments that could save their lives or improve their health, simply because no one has ever tested them on someone like them.
A team of researchers from universities and health trusts across the United Kingdom set out to map exactly how widespread this exclusion is and to understand the human side of the issue. They conducted a rapid review of existing studies, looking at research published between 2006 and 2025. Their goal was not to run new trials, but to gather every piece of available evidence about who gets included in non-obstetric trials—meaning studies about conditions not directly related to pregnancy itself, such as diabetes, cancer, or infectious diseases—and why. They wanted to know the actual numbers: how many pregnant people are allowed in? How many choose to join? And what stops them from participating? To ensure their work reflected real-world concerns, they also spoke with a small group of five contributors from the community, asking about their experiences with pregnancy, access to treatments, and their opinions on research to increase inclusion.
The findings reveal a stark reality. When the researchers looked at the data, they found that pregnant and breastfeeding people are included in a tiny fraction of clinical trials. In the studies that measured this, the rate of inclusion ranged from zero to just eight percent. In other words, for every one hundred trials testing a new drug or treatment, ninety-two or more explicitly ban pregnant people from joining. The situation is even more pronounced for breastfeeding individuals, with some studies showing inclusion rates as low as half a percent. The vast majority of the research the team reviewed focused on infectious diseases, such as HIV, Ebola, and the recent COVID-19 pandemic. This makes sense, as these are global threats where the need for data is urgent, but it leaves a massive void in knowledge about non-infectious conditions that also affect pregnant people.
The picture changes slightly when the researchers asked about willingness rather than actual enrollment. They found that the assumption that pregnant people would refuse to participate is largely incorrect. In several studies, between seven and ninety percent of pregnant women and people said they would consider joining a clinical trial if given the choice. The decision to say yes or no depended heavily on the context. If the illness they were facing was serious and the potential benefits of the new treatment were clear, many were willing to take a calculated risk. However, their willingness was often held back by a lack of trust in the safety of the specific interventions being tested and a culture of fear. Many participants expressed that they did not trust the interventions themselves, while maintaining trust in the research process and the researchers and health care professionals more generally.
The review identified six main themes that act as barriers to getting pregnant people into trials. First, there is a deep-seated fear of risk, not just to the baby, but to the researchers themselves, who worry about lawsuits or regulatory trouble if something goes wrong. Second, there is a genuine lack of evidence; without data, it is impossible to weigh the risks of a drug against the risks of the disease. Third, the culture of medicine is still built on exclusion, where the default answer is "no" rather than "how can we do this safely?" Fourth, there is a need for research that starts early in the process, rather than trying to add pregnant people in at the last minute. Fifth, financial concerns play a role, as trials that include pregnant people often cost more to run. Finally, there are practical issues, such as the difficulty of finding enough participants or the logistical challenges of managing care for a pregnant person during a study.
Perhaps the most significant finding is that the problem is not a lack of interest from pregnant people. The researchers found that the hesitation often comes from the medical and research communities, who have built a system designed to keep these people out. The review suggests that the current approach of blanket exclusion does not actually solve the problem of safety; it simply shifts the burden of decision-making onto individual doctors and patients, who are forced to make life-or-death choices without the necessary evidence. The authors conclude that to improve health outcomes for mothers and babies, the medical world must move away from automatic exclusion. Instead, they need to build a system where pregnant and breastfeeding people can choose to participate in research, with clear information about the risks and benefits, ensuring that the medicines they rely on are tested on people like them.
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