Reminds me of that scene from idiocracy about the genius couple that wanted kids but kept pushing it off until everything was “perfect”. Then they were too old and resented each other then died childless.
A strong family culture and the return of all the troops from ww2.
More younger people getting married and having kids. It seems like cost of living has a lot to do with it as well. Most people who want to start a family are waiting for a house but it is impossible for most to afford one.