Pregnancy Clinical Trials: Why Does Inclusion Matter?

What did pandemic research reveal about studying pregnancy?

A perspective published in July 2024 described staff experiences from a Gujarat cohort involving more than 600 mother–infant pairs. Researchers studied pregnancies with and without known SARS-CoV-2 infection, with household follow-up scheduled every six months over three years. Staff reported incomplete records, inaccurate contact information, fear and mistrust. These observations came from internal discussions rather than a formal survey of participants. [Frontiers in Public Health report](https://www.frontiersin.org/journals/public-health/articles/10.3389/fpubh.2024.1417712/full).

The project was observational, so this report cannot establish whether a medicine works or is safe during pregnancy. Its relevance to clinical trials is an operational inference: permitting enrollment cannot ensure meaningful participation when researchers cannot reliably reach eligible families. The authors proposed stronger records, trained staff and closer collaboration with healthcare teams.

Why do medicines need evidence specifically from pregnancy?

Pregnancy can affect a medicine's absorption, distribution, metabolism and elimination. Consequently, a dose studied in other adults may require additional investigation during pregnancy. WHO has warned that historical exclusion leaves gaps in knowledge about the safety and effectiveness of medicines and vaccines. These gaps matter when someone needs treatment while pregnant and clinicians must weigh potential benefits against uncertain risks. [WHO explanation of pregnancy research gaps](https://www.who.int/news/item/18-06-2025-equity-and-health--the-inclusion-of-pregnant-and-breastfeeding-women-in-clinical-trials).

In June 2025, WHO reported that an analysis of trials registered over the preceding decade found only 4% allowed pregnant women to participate. This describes trial eligibility across the registry analysis, not the proportion of participants who were pregnant. It also does not establish that every remaining trial should have enrolled pregnant women: the scientific question and potential risks still determine whether inclusion is appropriate. [WHO registry analysis summary](https://www.who.int/news/item/18-06-2025-equity-and-health--the-inclusion-of-pregnant-and-breastfeeding-women-in-clinical-trials).

How can pregnancy research become safer and more inclusive?

WHO's protocol-development resources recommend reviewing preclinical evidence and assessing anticipated benefits and risks before enrolling pregnant participants. The timing of exposure matters, so studies must consider gestational stage when interpreting outcomes. When researchers exclude pregnant or breastfeeding women, WHO recommends a scientific justification based on that assessment. Inclusion therefore requires a specific research plan; it does not mean every investigational medicine is suitable for pregnancy. [WHO protocol-development guidance](https://www.who.int/tools/knowledge-portal-for-inclusion-of-pregnant-and-lactating-women-in-clinical-trials/knowledge-portal/clinical/protocol-development).

Practical design also matters. WHO's 2024 clinical-trial guidance places patients and communities at the center of planning, delivery and communication. Applied to pregnancy studies, that principle means asking prospective participants whether visits, explanations and follow-up arrangements fit their circumstances. This is a practical implication of the guidance, rather than an intervention proven effective by the Gujarat report. Early involvement can help researchers identify obstacles before recruitment begins. [WHO clinical-trial guidance announcement](https://www.who.int/news/item/25-09-2024-new-global-guidance-puts-forward-recommendations-for-more-effective-and-equitable-clinical-trials).