It's not like this at all. People aren't having kids in all developed nations, east or west, and also in developing nations as they become more developed, the birthrate falls dramatically. It's not "anti-natal government policy", it's various other factors: cost of living, expectations of how much resources/attention will be devoted to each kid, women's rights, etc.

China's one-child policy is long since over, but their birthrate is very low too. Government policy isn't the problem (if it's even a "problem"). People just don't want to have big families, and now that they have a choice, they don't.

The one child policy was only ended in 2016. Several generations grew up under it, changing the culture significantly. That’s been true in all Asian countries.

> People just don't want to have big families, and now that they have a choice, they don't.

But “choice” is individualism! There are American subcultures that are more educated and affluent than average, like Muslims and Mormons, that have much higher fertility rates than average. And that’s because those cultures exert strong social pressures to conform to expectations about family life instead of leaving it to choice.

It’s not just East Asia. India is under replacement rate at this point and it’s been a constant drastic decline. It’s just a function of kids being expensive to raise with the standards a developed economy mindset imposes. Children become less of a throwaway/what will be will be proposition.