In developed countries, the fertility rate has declined from about 2.8 in the early 1950s to about 1.7 today. For developing countries as a whole, it has dropped from 6.2 in 1960 to about 3.4 today. Reaching replacement-level fertility does not mean that population growth levels off immediately. Two other demographic trends are especially noteworthy. First, the world's population is becoming more urban.
Urbanization is an important factor in the demographic transition to lower fertility rates.
When people move into cities, they have more job opportunities, their incomes tend to increase, and they have greater access to health and education facilities. As a result of these and other factors, their fertility tends to decline. Higher proportions of the global population living in urban areas should therefore help bring down fertility rates. Second, the world's population is aging. The most rapid changes are in the developing world, where the population over age 65 may grow by as much as 400 percent in some countries over the next 30 years.