What possible justification is there for suppressing/avoiding discussion of menstruation?

Are menstrual periods required for reproduction?

That’s news to me.
Growing up on a farm, we had horses, cows, dogs, cats, etc. – all of them reproduced quite abundantly, but none had any vaginal bleeding, etc. typical of a period. They all had estrus cycles, with fertile and non-fertile times (important to know when breeding), but not the symptoms discussed here.