Scientists Avoid Studying Women’s Bodies Because They Get Periods


Periods have been used to erect trumped-up barriers in front of women for decades: They’ve been cited as a reason women can’t be astronauts, why they can’t be president, and why they can’t do combat jobs in the military. Now, an editorial in the British Journal of Sports Medicine argues periods may be excluding women from another critical, male-dominated space: Clinical research.

The authors of the editorial, all researchers from the U.S. and the U.K., point to a 2014 review of thousands of sports and exercise studies that found that of over 6 million participants, only 39 percent were women. The gap persists despite the increased participation of women in sports and medicine.

Historically, part of the reason researchers have relied more on men is because of concerns over how clinical trials may affect pregnancy. But another reason, the authors say, is because “women were perceived as more physiologically variable.”

“The complexities of the menstrual cycle are considered major barriers to the inclusion of women in clinical trials,” the researchers argue.


By relying on men, scientists assume that they can get significant results with fewer participants and less funding. Periods, the scientists behind the editorial say, are just perceived to add another complicating variable — and are easiest to just avoid or ignore.

There’s still a massive gap of understanding

Crucially, even when research includes women, the authors find that studies are usually designed to include women early in their menstrual cycle, when their hormone levels are lowest — and are actually most similar to the hormones of a man — in order to “minimize” the impacts hormones might have on the study outcomes.

“It’s easier to test men, and if you are going to test women, it’s easier to either ignore the effects of the menstrual cycle or to test them in one specific phase,” Georgie Bruinvels, a PhD candidate at University College London and lead author of the editorial, told BuzzFeed News.

However, those results would only be scientifically vetted and meaningful for half the population. Women don’t stop exercising — or doing anything else — just because they get periods. By cutting out that subset of data, the research leaves a lot of gaps in our practical knowledge about half the population during a significant chunk of their life.


“There’s still a massive gap of understanding around what actually happens at all phases of the menstrual cycle. It’s the same for people on the oral contraceptive — we don’t know the effects of that either,” Bruinvels said.

This gap — both in overall representation and in menstrual studies — has real consequences for female athletes. For example, the bulk of the research on traumatic brain injury is done on men, even though women suffer from concussions at higher rates than men and take longer to recover in comparable sports. As a result, female athletes and athletic trainers are less likely to recognize concussions, and women are less likely to get crucial treatment. Some research suggests that there may actually be an interaction between concussion severity and the point where a woman is in her menstrual cycle — a potentially life-changing finding that research conducted only on men, or conducted only during one phase of women’s cycles, would fail to capture.

Periods, it seems, fall into a paradoxical zone — seen both as important enough to be a significant factor in medical research, yet not important enough to actually research.

The lack of diversity in medical research, however, is hardly restricted to sports medicine. For years, men have been used as a stand-in for women in medical research.

One place where the biological gender gap remains particularly high is in animal and cell studies. Most of this basic research is done on male cells and male animals, even when the therapy is likely to affect women more. Women are 70 percent more likely to suffer depression than men, for instance, but animal studies on brain disorders are five times as likely to be done on male animals.

Here, assumptions around period complications come up again. Scientists thought that the fluctuating hormones in the animals would complicate the research, but for many types of studies, the assumption turned out to be just that — an assumption. A 2014 study found that when it came to neuroscience research, “randomly cycling female mice were no more variable than males on any trait.”


Including women in clinical trials is more than just an issue of equal representation. It’s about ensuring that our treatments work just as well for women as they do for men. There’s a litany of examples of how the default-male medical design negatively impacts women’s health.

When Gender Stereotypes Become A Serious Hazard To Women’s HealthHealth by CREDIT: Shutterstock When Kathy tried to seek medical attention for abnormally heavy periods that were…thinkprogress.orgWomen are almost twice as likely to have adverse drug reactions as men, which may stem from the fact that medicine isn’t tailored to them. And the current body of medical research doesn’t necessarily take women’s symptoms seriously. Even though women are more likely to suffer from chronic pain — such as fibromyalgia, which almost exclusively affects women — they’re less likely than men to receive appropriate treatment. Painful conditions that exclusively affect women, like endometriosis, can go undiagnosed for years. And women are more likely to be misdiagnosed and sent home from the hospital when experiencing a heart attack, because the “classic” signs of a heart attack — crushing chest pain, tingling in the arm — are classic only for men.

Relying only on male medical specimens produces a skewed view of the world, and using men as proxies for women is simply bad science, according to Dr. Jerilynn Prior, a professor of Endocrinology at the University of British Columbia.

“Not scientifically correct. Period. Full stop,” she told CBC news.