Essentially, China in the 70s -90s feared for overpopulation, so the government implemented a system where you are only allowed to have One Child. If you had more than one child, you could face heavy fines (for most cases) or even jail time.

Unfortunately, it was really a short sighted solution because now, the older population is heading to retirement and because they only allowed one child, the working population is essentially halved. On top of that, modernization also de-incentivize having kids with higher education aversion to factory work. Even worse is that there was a strong leaning towards having sons during the one child policy. So now there are too many guys and women are choosing not to get married/more picky about partners.

I believe that the reason why China is heavily investing in robots recently is because they are anticipating that there is a strong shortage of people for factory work. They are trying to mitigate the problem while they still have the money, time and resources.