> Kids cost time, not money.

There's a well known aphorism about this...

Um, wtf is this rambling statement that doesn't seem to be based in any kind of truth at all?

In the past both poor and rich tended to have tons of kids, this is because kids tended to die young regardless of being rich or poor.

Then you're trying to compare massive social changes in the west that occurred around the same time. For example womens suffrage, women being allowed to work, sexual revolutions and birth control.

If you look at countries that tended to develop later, the rate of childbirth tends to drop with accessibility to birth control and education.