My daughter was at a friend's birthday today and I just got a text from birthday girl's mum with a heads up that periods came up in conversation. All very friendly - said my DD and one guest said they had read the same book about it - the other 2 girls want to borrow the book. I replied that I'd be happy to drop it off. Then other book-reading guest's mum replied that yes, her DD had the book "but has not read THAT chapter" and if her DD knows about periods it's news to her with sad face emoji. Now I feel I'm branded the weirdly irresponsible parent exposing kids to inappropriate information. I'm in the USA which I think makes a difference - but British. Do I reply or ignore? It's a group text for the 5 mums with girls at the party plus host. They are all 10 years old.