The pattern is well established. As societies grow wealthier and more secular, and woman gain greater agency, birthrates come down.

Well, urbanisation and our inability to plan cities for kids might, just might, have something to do with it. In the town I work 1/6 of families that live in urban neighbourhoods have kids, while it's 4/10-5/10 in areas of bungalows with proper gardens.

Add an unstable political/medical/economical environment and housing policy becomes relevant. In good times it might be ok to have kids while living in a city flat and plan for moving to greener pastures as it becomes necessary, but not if you can't count on having a job when it's time to buy a new house. And with the housing market being what it is today for first time buyers...

No wonder nobody wants to have a baby!