Is that supposed to be a problem? How does it connect to the story in your comment?

The question seems to be warranted to me, since being underweight can stop you from menstruating. So if you find someone thin and her last period was off in the distant past, you can conclude that there's a problem and something should be done about it; if it was a couple of weeks ago, you can conclude that she's fine.

(It could also just be something that is automatically assessed as a potential indicator of all kinds of different things. Notably pregnancy. For me, it bothered me that whenever you have an appointment at Kaiser for any reason, part of their checkin procedure is asking you how tall you are. I'd answer, but eventually I started pointing out to them that I wasn't ever measuring my height and they were just getting the same answer from my memory over and over again. [By contrast, they also take your weight every time, but they do that by putting you on a scale and reading it off.] The fact that my height wasn't being remeasured didn't bother them; I'm not sure what that question is for.)