This short fiction (short story or maybe novelette) could only have been written by a woman. I read it more than 10 years ago in a collection, but it is probably much older than that.
A middle age woman (the POV character) calls her mother (or perhaps her mother-in-law) to tell her that her daughter (just turned 18 IIRC) has decided to become a "Cyclist". The older woman does not see any problem about her grand-daughter doing some outdoor exercise. But "Cyclists" is not at all about riding bicycles but about menses!
It takes place in a possible near future, when a perfect treatment has been found to suppress menses, without any negative side effect whatsoever. (I think they can just stop the treatment when they want to get pregnant, and resume it just after the birth). So almost all women have adopted it, and give it to their daughters as soon as puberty starts. A very small percentage of women, who call themselves "Cyclists", choose not to take the treatment and persists in having menses. Some of them are very militant and try to proselytise others. Young girls turning 18 are obvious targets since they can now choose for themselves. In particular the daughter of the POV woman of the story.
There are a few rather hilarious pages where the whole family, mother, both grand-mothers, sister(s?), aunts, cousins, friends and acquaintances all discuss of the way to convince the girl to change her mind. Which she does, eventually, IIRC.
The story does deal of a serious medical-sociological problem, but in a very humorous way.