Answer:
The only solution to over-population is to raise the standard of education, standards of healthcare and also the standard of living of people. Once they do not need children to be cheap labour or sale goods (dowries) or insurance for one's old age, then people are open to reducing family size.
There is a phenomenon called Demographic Transition, which is when populations move from a stable low population with high birth rates and short life expectancy to a stable low population with low birth rates and high life expectancy. Most western countries are in that end phase.