Written by Rhiannon Davis. Reviewed by Jenny Wordsworth. 

Medical research has long been dominated by studies conducted on men and people, with the assumption that findings could be universally applied. However, the exclusion of people whose sex was recorded female at birth from clinical trials has led to significant data gaps, misdiagnoses, and ineffective treatments. Despite progress in gender-inclusive research policies, systemic biases persist, affecting everything from drug safety to fertility research.

A History of Exclusion

For much of modern medical history, women and people were deliberately excluded from clinical trials. Concerns over hormonal fluctuations and the potential risks to pregnancy meant that researchers prioritised ‘male’ participants, considering them "simpler" test subjects. In 1977, the US Food and Drug Administration (FDA) formally recommended excluding women and people of childbearing potential from early-stage clinical research, a policy that remained in place for over a decade.

In the UK, this bias was similarly entrenched. Historically, medical research prioritised male physiology, leading to treatments and medications developed without adequate testing on women and people. The 1990s saw a shift, with international pressure, including from the European Medicines Agency (EMA), to include people whose sex was recorded female at birth in clinical research. However, decades of male-centric research have already shaped modern medicine, and the legacy of exclusion continues.

The Data Gap: When Science Fails Half the Population

The exclusion of people whose sex was recorded female at birth from clinical trials has had lasting consequences. One of the most significant issues is the failure to recognise sex-based differences in drug metabolism. Women and people experience adverse drug reactions nearly twice as often as men, mainly because medications are still predominantly tested on male subjects.

Cardiovascular disease is a striking example of this bias. Historically considered a "man's disease," much of the research focused on those whose sex was recorded male at birth. As a result, symptoms of heart attacks in women and people were poorly understood, leading to frequent misdiagnoses and undertreatment. The British Heart Foundation (BHF) has reported that thousands of those whose sex was recorded female at birth in the UK die unnecessarily each year because they are less likely to receive correct diagnoses and treatment.

Similarly, conditions such as ADHD and autoimmune diseases have been widely studied in men despite disproportionately affecting women and people. A recent study from University College London highlighted that ADHD remains underdiagnosed in those whose sex was recorded female at birth due to outdated diagnostic criteria based on traditionally male presentations of the condition.

Fertility & Reproductive Health: A Research Blind Spot

While women have historically been excluded from many clinical trials, research on people whose sex was recorded female at birth has often been confined to reproductive health. However, even within this field, significant gaps remain.

Polycystic ovary syndrome (PCOS), which affects around 1 in 10 women in the UK, remains under-researched despite its links to infertility, diabetes, and cardiovascular disease. Endometriosis, another debilitating condition, takes an average of eight years to diagnose in the UK due to a lack of clinical awareness and research funding.

Fertility science itself has also suffered from these biases. Much of the research into preconception health focuses on sperm quality, while studies on egg health and the impact of lifestyle factors on female fertility are significantly underfunded. This imbalance reinforces outdated notions that fertility struggles are primarily a "female issue" while simultaneously failing to provide adequate scientific insights for those trying to conceive.

Trying to Conceive: The Missing Science

IVF protocols, too, are often based on standardised approaches rather than personalised treatments, partly due to a lack of diversity in clinical trials. This results in patients potentially undergoing unnecessary or ineffective treatments before finding the right approach.

What Needs to Change?

Clinical trials must consistently incorporate sex-based analyses to address these disparities rather than defaulting to male-centric models. In the UK, the Medicines and Healthcare Regulatory Agency (MHRA) could consider enforcing stricter diversity requirements in medical research, ensuring that studies reflect the populations they aim to serve.

Beyond institutional changes, there is a growing need for companies and organisations to support evidence-based approaches to female health research. By prioritising science-backed fertility solutions and advocating for more inclusive studies, we believe brands like OVUM can play a role in reshaping reproductive healthcare for future generations.

Key Takeaways

The exclusion of people whose sex was recorded female at birth from clinical trials has had profound consequences for medical science. While progress has been made, the road to truly equitable healthcare remains long. Recognising and addressing data bias is not just a scientific necessity, it is a matter of health justice.