India has gone negative, and Africa is the last of the positive birth rate countries.
China has been in decline now for 40 years, the one child policy and famines of the Mao era. Way under replacement from 1.7 per couple to 1.2 per couple.
Chinese hold two to four official IDs with different names, they buy them ... from the government, which is a long time thing, everybody does it on all sides so there is no one to arrest.
Korea are in suicide mode metaphorically speaking with half the replacement population being born, Japan is not so far behind.
There are a multitude of factors, which are direct, gradual and micro eugenics programs, which are not under way, but in the middle to end, in that the acceleration death, of "industrial diseases" cancer, heart, inflammation from food chain pesticides phthalates in plastics etc. long term exposure is just now kicking into high gear, as it takes decades ....
So the projection worldwide, accelerated decline in birth rate is a replacement rate of 1 per couple, which is a halving of the population per generation.
This is a mathematical thing, and nothing else.
The contrarians need to do the math before speaking.