David Ricardo wrote about this in the 1700s. He observed that people don't usually marry and have children until they have achieved the same level of economic security their parents had. When the economy is struggling or the productive classes are being squeezed, population growth stops or even reverses.

When Scandinavia's population growth went deep into the red in the 1800s, parasitic aristocratic fortunes were ruined, and the governments restructured with fewer monopolies, regulations and more equality in rights. Population started growing again.

The people who run the present system don't want it to change in a way that would allow the population to grow again. They'll do anything else, including nuclear war, before that...