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Pregnant and breastfeeding women should be routinely included in clinical research, where safe and appropriate, the British Pharmacological Society (BPS) has said.
In a position statement published on 18 March 2026, the BPS warned that longstanding gaps in evidence are leaving healthcare professionals and patients without the information needed to make safe and informed decisions about medicines.
In the UK, over 80% of women take at least one medication during pregnancy or breastfeeding, yet the “historical exclusion” of pregnant and breastfeeding women from clinical trials has “resulted in limited data on medication safety and efficacy for these women and their infants”, it said.
Among the recommendations outlined in the position statement, the BPS has called for pregnant women to be routinely included in clinical research.
It has also recommended a “pregnancy and breastfeeding investigation plan” to be introduced as part of the medicines licensing framework.
The BPS has also asked for greater use of post-marketing and real-world data, improved education for healthcare professionals on medicines use and safety in pregnancy, and standardised risk communication to provide balanced information about “medication use and the risks of untreated conditions”.
Zoe Van-Zuylen, lead women’s health and neonatal pharmacist at Imperial College Healthcare NHS Trust, told The Pharmaceutical Journal that the statement was “an important step” in highlighting how pregnant and breastfeeding women are being “underserved” in medication development.
“It is all too common to hear ‘it is not ethical to include pregnant or breastfeeding women in clinical trials’ but this can put women (and therefore their babies) at risk of poor outcomes in the future, as was demonstrated in the COVID-19 vaccine trials,” she explained.
Van-Zuylen also highlighted the importance of standardised risk communication, warning that women “are often getting very different advice, sometimes even from different healthcare professionals in the same organisation,” which can result in them “refusing important medications which are known to be safe in pregnancy”.
The statement noted that physiological changes during pregnancy can affect how medicines are processed in the body — potentially reducing efficacy or increasing risk — and that medicines can be transferred to the foetus via the placenta or through breastmilk.
It also stressed the importance of “maintaining good control of chronic health conditions” for the health of both mother and infant.
The BPS continued that healthcare professionals must have access to up-to-date information to be “confident to continue critical medications in pregnancy, where appropriate,” and that discussions with patients should cover the full “benefits, risks and uncertainties” of continuing, switching or stopping medicines during pregnancy.
Christopher Rentsch, associate professor of pharmacoepidemiology at the London School of Hygiene and Tropical Medicine, said that pregnant women were represented in only 1.1% of clinical trials and breastfeeding women in just 0.6% of trials submitted to the Medicines and Healthcare products Regulatory Agency (MHRA) between 2019 and 2023.
“The question should no longer be whether pregnant and breastfeeding women should be included in research, but how their inclusion can be done safely and responsibly,” he added.
Victoria Male, associate professor in reproductive immunology at Imperial College London, said insurance costs can discourage trial sponsors from including pregnant participants, noting that “unless the trial team has a strong motivation to include pregnant participants, the path of least resistance is to exclude them”.
Meanwhile, Jyotsna Vohra, director of research, programmes and impact at Tommy’s, the pregnancy and baby charity, commented: “Women and birthing people who experience health issues during pregnancy and while breastfeeding need to know that any medication they take will not only help to alleviate their symptoms but, crucially, will not harm their baby.
“They need clear information and reassurance about whether the risk of taking medication to control any long-term condition or deal with short-term illness is outweighed by the risk to their baby if left untreated.
“At the moment, it is simply not possible to provide that evidence-based information in the case of many medicines. We support moves to change that including the involvement of pregnant women and birthing people in trials in a way that is safe and appropriate for all the lives involved.”
The MHRA ran a consultation between July and September 2025 on how international guidance supporting the inclusion of pregnant and breastfeeding women in trials could be applied in the UK, with conclusions still awaited.
Louise Kenny, pro-vice-chancellor and chair of maternal and foetal health at the University of Liverpool, said the issue reflects wider underinvestment in women’s health research.
“Women deserve far better but this isn’t just about equity,” she said, adding that improving treatment in pregnancy could have long-term benefits for population health.
