“The seeds of change were planted in the early 1990s when the NIH began requiring that both sexes participate in human research. But this initial effort fell short because the NIH didn't require researchers to compare males and females, or to analyze enough participants of each sex to be able to establish whether there were differences in the ways male and female patients with the same condition present, or the effects of sex on the safety and efficacy of a drug or treatment regimen. It wasn't until 2014 that the NIH required that all animal research consider sex as a biological variable. This led to an explosion in work directly comparing the two sexes to establish whether significant differences exist.” Medical Research2024Sex And GenderNational Institute Of Health Book:On Sex and Gender: A Commonsense Approach Source: On Sex and Gender: A Commonsense Approach