Thing is, the marginal cost of kids has shot through the roof. It’s no longer a sensible thing to do - in the horrible times you mention, children were investments - you spend ~ 10years raising them, and after that they worked for you, almost free labor. And a lot more things required labor to function.
Now, kids are almost all cost, as the government / society itself captures their economic output, and doesn’t give enough back to the family that did the work to raise them.
So now you have kids because you want to, and its no longer rational act, more emotional one.