The conversation has moved on a long way while I have been watching a tribunal and reading those threads, but I want to add my experience at a girls-only school in the Swinging Sixties.
I don't think periods were ever mentioned. In Biology, up to age 14, we only got as far as cockroaches. Nothing about reproduction, theirs or anyone's. I didn't do Biology O level, anyway only the lower sets were allowed to take 'Human Biology' - what a useful course that would have been.
We had one lesson in the sixth form labelled "Sex Education" or similar. It was given by the unmarried Headmistress, a former Biology teacher, and was wholly about Venereal Disease, or STIs. We were not told how to avoid them, but I imagine total abstinence was implied.
There were at least two girls in my year who became pregnant. I still remember their names. They left the sixth form without explanation, but I saw them later.
One was probably the cleverest girl in the year. She got a full-time job at the shop where I worked on Saturdays. I hope she got a chance at higher education later, if she wanted it.