‘Concerning’ lack of female-only medical trials in UK, say health experts

British medical experts are raising concerns about the underrepresentation of women in clinical studies, The Guardian reports, with male-only trials outnumbering female-focused research by 67 per cent.

Healthcare professionals say they often have to make treatment decisions without enough sex-specific evidence, according to The Guardian’s analysis of comprehensive research data.

A joint investigation by the Medicines and Healthcare products Regulatory Agency (MHRA) and the University of Liverpool gathered extensive clinical trial data. The Guardian found that although 90 per cent of studies included both men and women, male-only trials (6.1 per cent) were far more common than those focused exclusively on women (3.7 per cent).

Pregnant and breastfeeding women were even more frequently excluded, taking part in just 1.1 per cent and 0.6 per cent of trials, respectively.

Dr Amy Brenner, an assistant professor in the clinical trials unit at the London School of Hygiene & Tropical Medicine (LSHTM), said: “It is particularly concerning that there are more male-only trials than female-only trials as, while they may be disease-specific, it is certainly not true that there are more male-only than female-only diseases.

Brenner said the imbalance could have serious consequences for women’s healthcare. This under-representation means there is a lack of evidence on the safety and effectiveness of many interventions in women.” She stressed the urgent need to address the gap to improve outcomes for women.

According to The Guardian’s findings, there were 282 male-only trials compared with 169 female-only ones. Participation by expectant and nursing mothers was particularly low—roughly one in every hundred trials.

Cancer research dominated the trial landscape, accounting for nearly a third of all studies. In contrast, cardiovascular disease—still the world’s leading cause of death—made up just 5.2 per cent. Studies on reproductive and maternal health were even rarer, representing only 2.2 per cent.

Professor Anna David, director of the EGA Institute for Women’s Health at UCL, said the “important” findings shed light on why new treatments for women’s health issues are slow to emerge, and why some women “are not getting the care they need.

There is this perception that women, pregnant women and breastfeeding women do not want to participate in clinical trials and therefore they are usually not considered as potential participants, even in phase 3 clinical trials. This is not the case,” she said.

David highlighted the lack of research into reproductive health issues as especially troubling. Pregnancy conditions such as pre-eclampsia, preterm labour, and placental insufficiency leading to foetal growth restriction are major diseases with no current treatments,” she said.

Professor Andrea Manfrin, the MHRA’s deputy director of clinical investigations and trials, said there was a “notable imbalance” between male-only and female-only trials. “When specific groups are not adequately represented in trials, it creates evidence gaps about how medicines work for them.”

Manfrin said the regulator was working with research partners to encourage more representative studies.

Health minister Karin Smyth said the government was committed to making the UK a global leader in life sciences, developing innovative treatments “focused on the conditions that matter most to patients”.