I think you were joking, but totalitarian regimes have done this before (Romania's orphan crisis was the result of similar policies, iirc).
The poverty/immigration dance - if you reduce poverty, women have less children. Eventually you reach the point where you need to allow immigration to provide enough workers to keep your aging population from starving. Immigration is an existential threat if your country is based on a single ethnic identity (e.g. Han). Immigrants are poorer and therefore have more babies, and at some point will become the ethnic majority, or at least a sizable minority, large enough to cause problems (and economically vital so you can't just round them up and deport them).
Getting middle-class people to have more babies is difficult.
Edit: of course, this isn't a problem if you don't base your country's identity on an ethnic identity.
The poverty/immigration dance - if you reduce poverty, women have less children. Eventually you reach the point where you need to allow immigration to provide enough workers to keep your aging population from starving. Immigration is an existential threat if your country is based on a single ethnic identity (e.g. Han). Immigrants are poorer and therefore have more babies, and at some point will become the ethnic majority, or at least a sizable minority, large enough to cause problems (and economically vital so you can't just round them up and deport them).
Getting middle-class people to have more babies is difficult.
Edit: of course, this isn't a problem if you don't base your country's identity on an ethnic identity.