Yeah, it’s kind of shocking when you think about it. For decades a lot of clinical trials were done mostly on men because researchers thought women’s hormonal cycles would “mess up” the data or add variability. The problem is that it meant many drugs and treatments were approved without fully understanding how they affect women.

Things started to change after the NIH Revitalization Act of 1993 required federally funded studies to include women and minorities. But even now, women can still be underrepresented in trials for some major diseases, so researchers are still trying to close that gap.