[blendo]

This rings true:

“Anderson's analysis shows that those born in 1891 could expect to inherit from their parents at the age of 37, while they still had children at home and when their oldest child was ‘at best only just entering the labour force’. By contrast, those born in 1946 could expect to wait until 56 before both parents had died, that is well after their children had left home, leaving middle-aged parents in the second half of the twentieth century vulnerable to economic constraints, particularly when they were sandwiched between caring for children and caring for elderly parents.”

[OneGuy123]

This. Moderne parents have children much later so the children might have to end up supporting their parents before they even have a familiy of their own which puts a huge financial strain on them, preventing them from having more kids.