No need to contemplate anything if your run-of-the-mill average job lets you support your entire family and purchase a house.
It's not like this only happened in the window between 1940s-1980s where the run-of-the-mill average job let you support your entire family and purchase a big enough house.
But if people cant afford kids they wont have them.
Its like super simple.
Talking about the educated West where people have the information and tools to make the decision.
Context inference is important