Why Have Women Historically Been Left Out of Medical Research?
It was only in 1994 that the National Institutes of Health (NIH) mandated the inclusion of women in clinical trials. It was in this year that the NIH Guidelines on the Inclusion of Women and Minorities as Subjects in Clinical Research were published, requiring NIH-funded investigations to ensure sufficient numbers of women included in clinical trials “such that valid analyses of sex differences in the effects of interventions can be accomplished.” A question very quickly formed in my head- why did it take so long to include women?
The NIH traces its roots much further back, to 1887. It began as the Marine Hospital Service, which later became the U.S. Public Health Service. Even in 1887, this “laboratory of hygiene,” as the physician in charge called it, worked to serve the public’s health. Yet since its inception, the vast majority of all advances made in human health through the NIH, now the world’s single largest funder of medical research, have largely been based on male populations. Furthermore, medical research conducted outside the NIH has predominantly recruited men in the past and is not bound to sex- and gender-inclusive guidelines. We’ve talked about why we should care to fix this problem, but where did it arise?
In other words, why were women not included to begin with?
The short answer is three-fold: women were excluded from medical research due to concern about exposure to experimental risk during childbearing years, a misperception that treatment is the same across sex and gender, and a belief that women’s menstrual and hormone cycle would bring unnecessary complications to the scientific design of experiments. Let’s look at each point more closely and then consider if they were justified.
1. Concern About Risks to Pregnant Women
This remains a legitimate concern. Pregnant women rightly should not be participants in a research trial that poses any potential risk to them or their child. However, the protection of pregnant women and their fetuses does not necessitate the exclusion of all female research participants. By excluding female participants of “childbearing age,” research has excluded a huge segment of women, those from life stages ranging menarche to menopause. Even more troublingly, this dictum ignores that some women may choose never to be pregnant. In fact, the emphasis on childbearing conflates women’s health with reproductive health. There are many more aspects of a woman’s health, such as her reaction to certain drugs or her unique symptoms from heart attack, which remained unstudied for so long for fear of losing or compromising reproductive capacity.
2. Misperception that Treatments Are Universal
Women were not actively recruited due to the belief that studies done on men would suffice or be just as applicable. However, we know now that presentations and treatment of illness or disease can be quite different in males and females. For example, a woman might present symptoms differently than a man when experiencing a heart attack, including symptoms that cannot be detected with the standard male-oriented test that checks for occlusion of the artery. Other examples of sex and gender difference abound. We can surely say that studies done exclusively on and for men might not provide the whole picture when diagnosing or treating women.
3. Belief that Women’s Menstrual and Hormone Cycles Are Confounding Factors in Scientific Studies
Indeed, there are variations in a woman’s body over time: changes in the time leading up to the first menstruation, on a monthly basis during menstruation, and as menstruation ends during and after menopause. However, there are also hormone changes in men, including decreasing testosterone levels with age. This reason for excluding women raises important questions. If information regarding women’s health is slightly more difficult to obtain in certain cases, does that mean it is not worth pursuing? When are the reasons, if ever, good enough to exclude women from participating in medical research?
While we are still grappling with those questions today, what is clear is that leaving women out of research leaves us with conspicuous gaps in knowledge in some areas of health and medicine.
