This is a slightly tricky subject, nobody likes talking about it. Especially dads when their daughters are growing up.
And perhaps that's why we have to take a deep breath, and tackle it.
Research out of Australia shows one in five girls will stay away from school, because they're embarrassed about changes in their bodies.
We've heard a lot lately about period poverty, and the government has stepped up with a scheme to provide products free in schools.
The social enterprise Dignity says the Australian research suggests we need to go further.
Co-founder Jacinta Gulasekharam joined Tim Dower.
“Unfortunately this roll out is just about products, it doesn’t encompass education.”