Bill Gates on whether improving health in poor countries will lead to a population explosion:
When the Gates Foundation started out, it emphasized “reproductive health,” a.k.a. population control. (Someone once noted that you can always convince poor people that rich people have too much money and rich people that poor people have too many children.) But they soon discovered that there’s a direct relationship between improving health and slowing population growth. The most effective way to get people to have fewer children is to rapidly improve the health prospects of those kids. Speed is important, because it gives parents a chance to react and have smaller families.
This implies that aid should be concentrated, to get a small group out of the Malthusian Trap, rather than to grow a larger group a bit faster than usual without improving their long-term situation.