Babies have flat heads these days

My friend has recently had a baby. I'm pregnant so I was over there the other day learning how to change a nappy. She was telling me how she was worried about the shape of the child's head. Sounds like a slightly over paranoid motherly reaction, but apparently not. The health visitor said that yes, indeed the baby's head is flat at the back, but its because now days we tell people to lay the baby to sleep on its back. This means that where we have rounded heads, all our children will have flat heads. Its perfectly normal and nothing to worry about. My concern is, how will this affect the hat industry. Will hat shapes change? Will vintage hats become obsolete? Too early to tell probably..