Technical advocacy

The exclusion of pregnant and lactating women from clinical research, has led to a lack of evidence on medication and vaccine safety and efficacy, increased potential health risks in this population, and has meant widespread off-label use or the use of medication without pregnancy-specific indications. Most medications taken during pregnancy and the lactation period have never been formally tested in pregnant and lactating women, meaning they are prescribed for unstudied conditions or in unstudied dosages. This can result in unforeseen side-effects, or reduced effectiveness, potentially harming both the woman and the fetus or infant, with the potential for long-term harm.

Health workers must perform risk–benefit evaluations without robust evidence to decide whether to continue current treatments or switch to alternatives, which may increase the potential for preventable harm. Additionally, it places an emotional burden on women to decide whether to use a medication or not without the necessary evidence to guide them. A lack of formal evidence does not mean these medications are without risk, underscoring the urgent need for rigorous research in this population.

Pregnant and lactating women must be protected by including them in ethical research that generates pregnancy- and lactation-specific evidence. When provided with accurate information and respectful support, pregnant and lactating women should be recognized as empowered partners in research. Studies involving this population require distinct considerations compared to those involving non-pregnant or non-lactating participants. Closing this evidence gap is essential to advance women’s health, strengthen health systems, and ensure equitable access to safe and effective treatments across the life course.

The World Health Assembly Resolution WHA75.8 (May 2022) calls for the equitable, standardized inclusion of under-represented populations – such as pregnant and lactating women – in clinical trials. The inaugural WHO Global Clinical Trials Forum (November 2023) highlighted the urgent need to implement this call.

To support this transformation, the WHO Pregnant and Lactating Women Task Force was established in 2025. The group has developed this living Knowledge portal to promote inclusive research practices for those medicines, vaccines, and biologicals that were initially intended for non-pregnant populations but which could also benefit pregnant women and address both pregnancy-related and non-pregnancy conditions. The Knowledge portal includes crosscutting, general strategies applicable across diseases, as well as targeted guidance for specific non-pregnancy and pregnancy-related conditions.

While the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH) guidance specifically addressing the inclusion of pregnant and lactating women is still under development – and will be primarily intended for drug developers and regulators – this Knowledge portal aims to provide researchers, programme implementers and community representatives with high-level considerations and practical resources to support the ethical and timely inclusion of pregnant and lactating women in research. Where authoritative documents already exist, the Knowledge portal references these sources and highlights key points for easy and practical reference.