And people stay in (inner) cities longer. Before, people had kids earlier and they moved to the suburbs when they had kids. Now they have kids later and more and more stay in the city even after having kids.
This does not sound like a public policy solution, but parents paid more for bigger flats
What newer apartment blocks brought was an option to stay in the city. Surely a 3-bedroom apartment with a big living room and a kitchen costs more, but prices are comparable with own houses in far away suburbs. That gives an option to stay with kids if not in the city center then at least within a short ride from it in public transport.