Generally, as countries advance in their social and economic development, their populations will boom (many people, even poor people, will see some form of positive financial growth, this opens up people to having more children), but then as time moves on, population growth will stagnate. This is induced by many factors but really boils down to the influence capitalism has on human psychology, it’s not healthy for humans to exist in a capitalist society, and no matter where you are, no matter the country, that will eat at you in time, consumerism rots your brain and makes you feel like shit. It’s the general social malaise everywhere you go. I’m sure most people have heard, especially younger folks “why would I bring kids into this fucked up world” it’s a rampant mindset and it’s what we are fighting against as communists.