Many third world countries are trapped in a vicious circle. Because there is no functioning social security system, it is important to have many children because they will provide income for your family in the future. So on a micro level this makes sense. But on a macro level it is disastrous because the population growth will put even more pressure on your social security system.

The draconian policy of China enabled it to spend more resources on economic development. It is not so long ago that China was also a typical third-world country.