> The one-child policy worked.

If you ignore the invasive health monitoring, gender selective abortions, forced abortions, and other human rights violations, sure.

But I'm not sure this cure wasn't worse than the disease. Especially, as you point out, since fertility rates seem to regulate themselves in developed countries.

I guess if you're a pure utilitarian, you could try to make the case that it all was a net benefit, but I don't see many utilitarians around these days.