In 1850 you might have a few more kids, thinking they could farm more and through hard labor your family could break even on resources. Your family of 8 all shares a single bedroom and you only send the smartest kid to high school (begrudgingly).
In 2024 people are putting off children because they won’t be able to afford a nanny, because the price of globally-sourced instantly-available groceries are too high, or because they are feeling their life already has enough richness and direction. If I cared for my children in the way we used to during population explosion they would be taken by CPS.
The inflection point where our global population levels out will be Interesting Times, but I’m optimistic for the long term sustainable culture that may result.