Agree that the male teacher bringing up the subject of periods for primary school aged girls seems very unusual and at least 20 years too soon. Whereas now it's quite common for girls to start when they're 8, 9 or 10, in those days it was highly unusual (and very unlikely a male teacher would have been the one to bring it up!).
Also felt wrong that Trixie was sneaking back into Nonnatus House in the morning after a night of passion. It seemed quite disrespectful and given how well-brought up she is, I'm not sure she would have been doing 'the morning walk of shame'?
Nurse Crane seems to very much feel what her beloved girls are going through, doesn't she? She has very much the same type of relationship with Lucille as she did with Barbara.