Think of three social factors that contribute to lower birth rates in the countries farther along. How might these social conditions be encouraged to emerge in less developed countries?

Women participation in the labor force: women who have careers and jobs tend to have less children, either because the put off motherhood to focus on career, or because they have less time.
Access to contraception: in other word, birth control. These factor keeps women from having unwanted or unplanned pregnancies.
Urbanization: everywhere around the world, people who live in cities tend to have less children than people who live in the countryside. This might have to do with the frequent reduced living space in cities, the lack of need for child labor (people in farms frequently use children for help in agricultural tasks), and the more costly and fast-paced living style.

In developing countries, women can be promoted into the labor force by helping them access education. Laws demanding firms to hire a certain percentage of women (quotas) can be enforced.

Access to contraception can be widened by educating women in how to use these methods, eliminating prejudices and preconceptions. They could also be handed out for free in poor, vulnerable communities, or they can be subsidized.

Urbanization does not so much advocacy because cities are attractive to most people: they are places where job opportunities are better than in the countryside, and all over developing countries, people are moving to cities from the countryside.