Before I got sick, I probably would have said I had a lot of trust in medicine. Not that I’d given it much thought; as a healthy twentysomething, I’d at that point had little need to. But I believed in science, and I viewed medicine as an extension of science.

Sure, I knew that women had been almost entirely excluded from the medical profession until the mid-’70s. And I knew that the medical men of centuries past had some absurdly sexist theories — like that getting a higher education would cause women’s uteri to atrophy or that women’s smaller brains put them lower on the evolutionary ladder. As a longtime feminist writer, I certainly knew, intellectually, that scientific “objectivity” is a myth; that researchers, like all of us, cannot help but bring their biases to their work; that it affects the questions they ask, and the questions they don’t ask. Still, I had enough faith in science — in its ability to be a force for progress and truth — that it seemed like a few decades was probably long enough to overturn the sexist legacies of a historically male-dominated medical system.

Above all, I just hadn’t worried too much about it — that is, until several years ago, when my immune system started attacking my joints. I was diagnosed with rheumatoid arthritis and became one of the estimated 50 million Americans, three-quarters of whom are women, with an autoimmune disease.

As I learned more about autoimmune diseases, I discovered just how lucky I’d been to get diagnosed within several months. According to a survey by the American Autoimmune Related Diseases Association, patients with autoimmune diseases see an average of four doctors over four years before they are accurately diagnosed, and nearly half report being labeled “chronic complainers” overly concerned with their health during that search.

As I started asking among my social networks if other women had had similar experiences, it turned out it wasn’t just women with autoimmune diseases who had struggled to get health-care providers to take their symptoms seriously: There was a friend whose abdominal pain and incontinence from a ureaplasma infection was diagnosed as “stress.” There was another friend experiencing dizziness, wooziness, ringing in her ears, and floaters in her eyes from West Nile virus who was referred to a therapist for depression. Another who’d been told her stabbing chest pain from pericarditis, inflammation of the lining of the heart, was likely just anxiety. The list went on.

After spending the past few years writing a book about gender bias in medicine — and hearing from nearly 200 women with similar tales of having their symptoms dismissed, belittled, or disbelieved entirely — I’ve realized that doctors just aren’t equipped with the knowledge they need to be able to provide care for their women patients as well as they can for their male patients.

For decades, women were largely left out of clinical research, a problem that wasn’t even on the radar until the early ’90s. Even today, analyzing research results by gender to determine if there are any differences between men and women still isn’t the norm, even though we increasingly know there often are differences — in everything from drug metabolism to the symptoms of a heart attack. Preclinical research on animals and cell lines still skews to male subjects. Many conditions that disproportionately affect women — including endometriosis, fibromyalgia, vulvodynia, interstitial cystitis, and chronic fatigue syndrome — are still very poorly understood, yet receive minuscule amounts of research funding. And since medical education evolves at a snail’s pace, much of the new knowledge about women’s health that has emerged over the past few decades still hasn’t made its way into clinical practice.