I had seen my mother's packets of sanitary towels in the bathroom cupboard from an early age. When I asked aged 3 or 4 what they were for, my mother said grown-up women used them once a month and that we didn't need to talk about it until I was a big girl.
When I was about 11 and the first slight signs of breasts developing showed, Mummy sat me and a slightly older friend, whose mother was too embarrassed to discuss it with her daughter down and told us why women have periods and that we would have them once a month unless we were going to have a baby, until we were 45 or 50, when periods stop again, and you no longer can have a baby.
We discussed sanitary protection, but having grown up in a doctor's household I knew and had told my friend too where babies came from, as I had often seen ladies with large tummies in the waiting-room, and the local midwives dropped in frequently for coffee with the family, and afterwards a chat behind closed doors with Daddy about Mrs some-one or other who was having a baby.
We were five doctor's daughters, a midwife's daughter and two nurses' daughters in my class at school. Our Scripture teacher got very, very cross when we all started laughing at the Hebrew midwives telling Pharaoh that the Israelite women gave birth so quickly that the midwives, who were supposed to be killing the boy children couldn't get there.
We knew very well that it takes hours for a baby to be born.
We were the classroom authorities on the subject of babies, periods etc.