In the 1983 movie Yentl, the title character, played by Barbra Streisand, pretends to be a man to get the education she wants. She has to change the way she dresses, the timbre of her voice, and much more to get any respect.

In medical lore, the term “Yentl syndrome” has come to describe what happens when women present to their doctors with symptoms that differ from men’s — they often get misdiagnosed, mistreated, or told the pain is all in their heads. This phenomenon can have lethal consequences.

Many, many women have had this experience when they go to the doctor. I had it myself, years ago. As a spate of articles about the phenomenon has come out in the past couple of years, more people have begun talking about a “gender pain gap.”

In a new book, Invisible Women: Data Bias in a World Designed for Men, the British journalist and feminist activist Caroline Criado Perez argues that this is part of a larger problem: the “gender data gap.” Basically, the data our society collects is typically about men’s experience, not women’s. That data gets used to allocate research funding and make decisions about design. Because most things and spaces — from pain medications to cars, and from air-conditioned offices to city streets — have been designed by men with men as the default user, they often don’t work well for women.

Even when researchers do gather data from women as well as men in their studies, they often fail to sex-disaggregate it — to separate out the male and female data they’ve collected and analyze it for differences. That’s crucial, because a new pain medication that’s ineffective for men may work great for women, but you’d never know it if you mixed all their data together.

All this gives rise to a powerful possibility: What if we can reduce suffering for half the population, simply by ceasing to design everything as if it’ll only be used by men?

Criado Perez’s book discusses how biased design shows up pretty much everywhere, but the issues she identifies in the realm of health are the most striking because they’re the most dangerous.

I spoke to Criado Perez about why the medical system treats women’s pain differently, whether we need to design drugs specifically for women, and how she dealt with the gaslighting she experienced while working on the book. A transcript of our conversation, lightly edited for length and clarity, follows.

Sigal Samuel

You write that the medical system is “from root to tip, systematically discriminating against women, leaving them chronically misunderstood, mistreated and misdiagnosed.” Can you start by explaining how the system got this way?

Caroline Criado Perez

It’s always been this way. And it comes from the fact that the male body has always been taken as the standard human being. The female body is seen as the atypical body. You see that going all the way back to Aristotle — he refers to the female body as a mutilated male body — and you see it in textbooks today, where the male anatomy is presented as the anatomy.

I don’t think there’s some giant conspiracy and medical researchers all hate women and want us to die. It’s just that this way of thinking is so pervasive that we don’t even realize we’re doing it.

That’s partly because of the excuses we still get [from medical researchers], which are outrageous — like the excuse that women’s bodies are too hormonal and too complicated to measure. Male bodies can be very variable, too. And women are 50 percent of the global population!

Sigal Samuel

To me, one of the most striking findings in your book is that in the UK, women are 50 percent more likely to be misdiagnosed after a heart attack, according to Leeds University researchers. That stems from the fact that heart failure trials typically use male participants. And when we picture someone having a heart attack, we picture a middle-aged man clutching at his chest or arm, like in a Hollywood movie.

Caroline Criado Perez

Yeah, and it’s actually been heartbreaking because since publishing the book, I’ve had quite a few people get in touch with me about heart attacks, saying, ‘My mother died of a heart attack because she didn’t present with the ‘typical’ male symptoms.”

The fact that we are still misdiagnosing these women is shocking. We call female heart attack symptoms atypical, but they are actually very typical — for women. And we’ve known about the female symptoms [like stomach pain, breathlessness, nausea, and fatigue] for a long time now, because cardiovascular research is the field where the most work has been done on sex differences. [Misdiagnoses continue in part because some doctors practicing today were trained on medical textbooks and case studies that depict heart attack victims as men.]

I have no idea how I’m going to cope when my mum dies. But I know that if she dies because of something like that, I will just be so angry.

Sigal Samuel

A study published in Brain in March offered new evidence that men and women have different biological pathways for chronic pain, which means some pain medicines that work for men may not work for women. Do you think we should be designing drugs that are specifically made for women?

Caroline Criado Perez

I’m not a medical expert, but absolutely it’s something that needs to be looked at. The fact that women may experience pain differently is something I came across a lot in my research. And yet the vast majority of pain studies have been done exclusively on male mice.

Sigal Samuel

Can you give an example of a drug that’s been found to be less effective for women?

Caroline Criado Perez

The most shocking one was a heart medication that was meant to prevent heart attacks but at a certain point in a woman’s menstrual cycle is actually more likely to trigger a heart attack. That has to do with the problem of not testing the drug on women at different stages of their menstrual cycle, because you [the researcher] say, “Oh, that’s too complicated and too expensive.” You’re basically saying, “I would rather let women die than have to do a complicated test.”

What I actually find most interesting is this: Women have more adverse reactions to drugs than men, and while the number one adverse reaction in women is nausea, the second most common is that the drug just doesn’t work. That is partly because [in drug testing] we are — from the cell stage to the animal stage to the human stage — not testing in women. It’s particularly bad in the cell stage as that’s where a lot of drugs get ruled out.

Sigal Samuel

It’s really striking to me that some drugs out there are not just less effective for women, but are actually potentially harmful for us. Since encountering these studies in your research, have you been telling the women in your life, “Hey, you should maybe look at this study and talk to your doctor about it?”

Caroline Criado Perez

Absolutely, yeah. Women have to be aware of this, because the medical profession is not. At least, it’s insufficiently aware of it and not worrying about it enough. It’s really unpleasant actually, because ever since researching this book I wonder, can I trust my doctor to know what the best thing is for me? I don’t know if I can.

Sigal Samuel

You talk a lot in the book about how everything is designed around the body of a “Reference Man.” Tell me about him.

Caroline Criado Perez

[laughs] Ah, my good friend, Reference Man. He is considered the standard human and he is a man. Usually a white man in his 30s, around 70 kg [155 pounds]. He’s the person we’ve used for decades in all sorts of research on the dose of the drugs.

When you get an over-the-counter medication, it doesn’t tell you male and female doses — it says “child” and “adult,” and that adult is a man. It’s Reference Man. To me, that shows the scale of the problem we have here. All these drugs need to be looked at to see whether male and female doses should be different.

In fact, they found that was the case for Ambien. Women were driving to work still under the influence of this sleeping pill and crashing their cars because the dose was too high. In 2013 the FDA had to tell women to cut their dose in half because it turned out they were metabolizing the active ingredient twice as slowly [as men]. The “gender-neutral” dose was anything but.

Sigal Samuel

Wow. And Reference Man also has implications for car crashes, right?

Caroline Criado Perez

Yes. Reference Man is who cars are designed for. For decades, the typical car crash test dummy has been based on the 50th percentile male. That means seatbelts are not designed for the female form, and women have to sit further forward because the pedals are too far away. So women are 17 percent more likely than men to die if they’re in a car crash. And they’re 47 percent more likely to be seriously injured.

Now there are female crash test dummies, but it’s just a scaled-down male dummy. In the EU, out of the five regulatory tests that must be done, the female dummy is only used in one of them, and it’s only used in the passenger seat. That is just completely mad.

A lot of examples are just down to people not having thought of something — like when Apple forgot to include a period tracker in its comprehensive health tracker app (even though it did include “copper intake”!) — that’s a case where they clearly just didn’t remember periods were a thing. But in a case like this, it has been brought to [car designers’] attention, and yet it’s still happening.

Sigal Samuel

There have been some attempts to force researchers to include women in their studies. Have they been effective?

Caroline Criado Perez

In the US, with the National Institutes of Health funding, there’s a regulation saying women must be included in human studies. In 2016, the same came into force for animal studies. But how rigorously is this being enforced? Not very.

In the EU, I’m not aware of any research that’s been done into how successful it’s been, but definitely the regulation is there that if you want funding you have to include women and sex-disaggregate your data.

The issue is that a lot of the research is being done by private companies, for which there is no regulation. And for generic drugs, again, there’s no regulation on including women.

Sigal Samuel

I’m curious about the emotional process you went through as you researched this book. Can you tell me what you felt?

Caroline Criado Perez

It was a building anger and frustration. And not feeling able to quite believe what I was discovering. It’s so explosive and outrageous, and you just feel like, how is it that this isn’t something everyone is talking about? You start to wonder: Am I going mad, am I making this up?

My way of getting through it was to speak to a lot of experts — doctors, anthropologists — because I wanted to be sure this wasn’t some sort of big misunderstanding.

And then after the book was published, some of the reactions from men have been, “You’re making this up, you’re crazy, this is not a real issue.”

Sigal Samuel

It strikes me that there’s a kind of meta-gaslighting here. On one level, women who present to their doctors with certain symptoms sometimes get told, “You’re crazy, it’s all in your head,” because their symptoms don’t conform to male symptoms. Then when you come along and try to study that as a phenomenon, you yourself have to wonder, “Wait, am I crazy for even thinking this is a phenomenon?”

Caroline Criado Perez

You’re really making me think now. I wonder... If I were not a woman and I weren’t so used to being told I’m crazy, would I have doubted and questioned myself so much while reading the research?

Sigal Samuel

I wonder that too. Looking to the future, what do you want people to do to fix this problem? Do we need legal change? A new field of gender-specific medicine? New textbooks?

Caroline Criado Perez

I don’t think I want a new specialization of gender-specific medicine. Because I want that to be the standard. Legislative change needs to happen — governments need to weigh in on this and enact legislation about how research gets done, specifying that it has to be sex-disaggregated. It’s also important to have women in positions of leadership, whether that’s the person doing the research or the person making the funding decisions. Women are more likely to be aware of female-specific needs and that will change the kind of research they think needs to get done.

Sigal Samuel

Overall, do you feel hopeful or hopeless that this problem will change in the near future?

Caroline Criado Perez

Ultimately I think it’s so outrageous and so ridiculous that actually what’s needed is for enough people to become aware of it, and then it will change. The evidence in the book — you can’t read that and think this is okay. It’s very clear: Women are dying. Unless you think it’s okay that women are dying, you must want to change it.

Sign up for the Future Perfect newsletter. Twice a week, you’ll get a roundup of ideas and solutions for tackling our biggest challenges: improving public health, decreasing human and animal suffering, easing catastrophic risks, and — to put it simply — getting better at doing good.