In a shocking recent essay, Lena Denham, the 31-year-old actress and writer, shared her decision to undergo a hysterectomy – surgical removal of her uterus – to end her long, painful struggle with endometriosis. She explained that terminating her fertility was worth the benefit of alleviating the pain and suffering she had been experiencing for years as a result of her condition.

Dunham isn’t the only young woman whose hysterectomy made it into the limelight: the BBC recently reported the case of a 28-year-old woman who suffered from a myriad of psychiatric symptoms, including suicidal thoughts, every single month prior to her period. Because standard pharmaceuticals offered no relief for her premenstrual dysphoria disorder, she too went under the knife to remove her uterus, and now lives peacefully with her family and is finally able to pursue her career.

Dunham’s decision – like many of her decisions – was met with dismissive think pieces. Experts who had no background about her medical history pronounced her decision flawed, as if it were the flippant choice of a hapless millennial, not a self-assured young women who was simply tired of suffering and had run out of other options. But the really interesting question here isn’t about analysing a famous young woman’s extreme life choices, rather, it’s why medical research has failed to deliver better solutions to women who are suffering.

The answer has to do with a dirty secret of medical research: a lot of the stuff we think we know about humans, we actually only know about men. Why? Because medicine still sees the female body as an unruly variant of the male base model, an obstacle rather than an opportunity.

For years, researchers have been reluctant to include women as clinical trial subjects, claiming that cyclical fluctuations in oestrogen and progesterone added too much variability to data sets. It’s not rocket science to run the statistical analysis and include enough women in the subject pool so that hormone phase can be used as a statistical factor. Even when studies do include males and females, many do not statistically analyse sex or cycle phase as a factor. This means that valuable information about whether a drug or its side effects is more impactful in males or females is lost. But researchers too often adopt the blunt approach of defaulting to male subjects and assuming their findings will be relevant for female physiology.

The irony, of course, is that drugs that were not sufficiently tested on women (because of concern about how women’s bodies might react) may then go on to harm women. The most famous example of this is the insomnia drug Ambien. Once Ambien was on the market, it was prescribed to men and women at equal doses. But, only after the drug was being widely prescribed and women were suffering did the problem become clear: Ambien takes a longer time to clear from the system of women than men, dangerously increasing the risk for overdose and adverse side effects for women.

When research in this area does occur, too often it’s about trivial socio-sexual differences which are then sensationalised by the media, like what types of men women find most attractive during their fertile window (shocker: a meta-analysis of over 50 studies found no significant link between menstrual cycle and partner preference qualities) or whether strippers receive more tips when they’re ovulating (a study which everyone seems to have heard of, even though it only looked at 18 subjects for only two months).

We have major blind spot in medical research: we either pretend that women’s bodies are the same as men’s, or treat their differences as trivialities to share in the pages of Cosmo magazine. These two extremes—ignoring physiological differences between the sexes or only focusing on them in the most superficial ways—miss the obvious ideal middle ground: acknowledging that the menstrual cycle is a basic physiological phenomenon affecting half the population at some point in their lives, and taking it into account when doing medical research.

A stunning lack of appreciation for female physiology has slowed progress in women’s health research. We’re behind where we should be in understanding how the menstrual cycle impacts overall health, and how cyclical hormonal changes impact conditions like asthma and migraines and are even related to the risk of developing serious conditions like Alzheimer’s and heart disease. We still routinely prescribe women powerful medications—like sleeping pills and anti-depressants – without understanding the impact they will have on female physiology. And we’re still leaving women like Lena Dunham with too few options for dealing with her chronic menstrual pain, leading to her taking the extreme measure of having a hysterectomy at age 31.

So what can we do?

We can toss the broken record player and upgrade how we talk about the cycle to break down the menstrual cycle stigma. We need to challenge it culturally – meaning the way we talk about it in conversation – as well as in medical research – meaning we need research to study the cycle, in relation to reproductive and general health.

Medical research should aim for equality, but equality is more complex than equal numbers of male and female subjects in experiments. Women are biologically different from men, and equality in research means using those differences as opportunities to understand men’s health and women’s health so that both genders equally benefit from medical research.