 It was really just a correlation. This is just sort of a basic question, but how well researched is menstruation? You know, it's something that roughly 50 percent of the population does in their lives at some point. But how much do scientists really know about it? I'm so glad you brought this up. And it's interesting because a few years ago, our study team just looked up the search term of menstruation in the PubMed database.