Actually, in the US, there is a great deal in terms of legislation and policy that prevents boys being taught about menstruation. Either alongside girls or separately. Sex Ed and even reproductive biology are sometimes not taught in schools at all. This is one reason why the abortion debate is so frustrating. A large segment of our population is ignorant as to how female reproductive systems work.
As a for instance, when I was in high school I took an advanced level physiology class. This included dissecting a cat. We were required to memorize and diagram all of the bones, muscles, organs etc. Except for anything to do with the reproductive system. We couldn't cover that chapter either. Be ause that was considered to be sex ed. This was in a good school in a liberal area. So you can't have any expectations that any of these legislators fully understand pregnancy.