Women are not ‘little men’– experts call for clinical trials overhaul to close the gender health data gap

Experts have called for an overhaul of clinical research, warning that women are not ‘little men’ and are still being systematically excluded from the evidence used to shape healthcare.

According to a panel of leading figures from across the world of health, femtech and law, women remain underrepresented in clinical research, treatment pathways and the AI-driven models increasingly used to inform clinical decision-making. The consequences, they warned, are significant. Women spend around 25% more of their lives in poor health than men, are more likely to have their symptoms dismissed, and face longer delays in diagnosis and treatment.

The panel called for all clinical trials – not just publicly funded studies – to be mandated to include a minimum proportion of women, and for researchers and commercial sponsors to routinely collect female-specific data such as menstrual cycle stage, menopause status and use of HRT. It is extraordinary, panellists noted, that trial participants are asked for everything from their weight to what they ate for breakfast, yet no one asked 51% of the population whether they are having periods.

The discussion forms the fourth and final instalment of FemHealth Focus, a four-part series of reports on women’s health commissioned by leading UK law firm Mills and Reeve. The latest edition, published today, examines how gaps in health data are holding back diagnosis, treatment, innovation and investment. It sets out a powerful call-to-action for policymakers, researchers and industry to build a more inclusive evidence base that turns the ambitions of the government’s renewed Women’s Health Strategy for England into reality.

Professor Dame Lesley Regan, Women’s Health Ambassador for England, Chair of Wellbeing of Women, and Professor of Obstetrics and Gynaecology at Imperial College London, took part in the roundtable. She said: “There is a persistent myth that because women live longer than men, they are healthier. In fact, they live far longer in poor health – and, unlike men, the burden isn’t concentrated at the end of life. It falls in the years between 18 and 55, when women are working, raising families and caring for older relatives. The cost isn’t measured just in lives lost, but in economic and social participation. Ensuring women are properly represented in the data that shapes their care is not a niche concern, it is fundamental to the nation’s health and prosperity.”

Despite the introduction in 2024 of a mandatory requirement for female participation in studies funded by the National Institute for Health and Care Research, there are still no minimum requirements for the proportion of women included in clinical trials. Only 5-14% of studies examine outcomes by sex, despite marked sex-based differences in response to the same drugs and treatment.

The data gap is also stifling innovation and investment. Just 2% of venture capital healthcare funding in the US is allocated to women’s health, while femtech accounts for less than 2% of total health tech funding. According to McKinsey, closing the gender health gap could unlock $1trn in global GDP by 2040.

The discussion also examined the ‘double edged sword’ of AI in women’s health, with the resulting report calling for a legal duty on large online platforms to distinguish between sexually explicit material and legitimate health education. This comes after research by advocacy body CensHERship found 95% of women’s health content creators had experienced some form of censorship on social media.

Steph Caird, partner at Mills & Reeves, commented: “We are witnessing a fundamental shift in how women’s health is viewed. No longer seen as a niche area, it is now firmly in the mainstream of healthcare, research and innovation. We are seeing increasing investment, greater policy focus and a growing commitment across industry, academia, the NHS and government, which is reshaping how we develop and deploy diagnostics and treatments for women.

“The opportunity now is to build on that momentum and to address longstanding gaps in our knowledge of women’s health. By improving the collection and use of female-specific data, and ensuring women are appropriately represented in research, we can strengthen the evidence base that underpins innovation, support the development of new products and services, and ultimately deliver better health outcomes for women.”

The panel additionally called for practical steps to boost women’s participation in research, including flexible schedules, remote access, opportunities to join studies through routine care appointments at women’s health hubs, and greater investment in community-led engagement to build trust among underrepresented groups. As the report puts it, no one is hard to reach, but some people are very easy to ignore.

Sophie Burton-Jones, partner at Mills & Reeve, added: “The opportunity presented by AI and digital technologies in women’s health is enormous, with the potential to support earlier diagnosis, more personalised care and better outcomes. But these tools are only as good as the data and systems that underpin them. If AI is built on unrepresentative datasets or a male-default evidence base, it risks amplifying existing inequalities rather than addressing them.

McKinsey’s recent analysis of the £36 billion opportunity from closing the UK women’s health gap underscores why this matters. Real progress will depend not only on better data, but on inclusive design, equitable digital access and access to reliable, medically accurate information. As healthcare becomes increasingly digital, platforms and providers must be accountable for ensuring trusted women’s health content is visible and accessible to all.”

Charlotte Lewis, principal associate at Mills & Reeve, concluded: “Despite around 70% of femtech companies having at least one female founder, female founders raise 23% less capital per deal than male founders.  Until the evidence base improves, female founders will keep being asked to prove a commercial case with data the system has never bothered to collect.”