"Fertility rates have generally been declining since the 1960s. Worldwide, total fertility is currently estimated to be about 3. 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. In the poorest developing countries, however, it is still about 5.6 (5).
Reaching replacement-level fertility does not mean that population growth levels off immediately. Even with fertility below the replacement level, countries with large numbers of couples in their reproductive years will continue to grow for some time because of "demographic momentum" ; that is, each woman is having fewer children, but many more women are giving birth.
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 world's population currently is growing at a rate of about 1.5 percent per year (6), but because of past levels of high fertility coupled with declining mortality rates, the population over age 65 is increasing at an annual rate of 2.7 percent. 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. There will also be a dramatic rise in the number of people over age 80 (7)."
wri.org
There is more detailed information at un.org but it is older.
A graph with data through 1995 and 3 different projections for the future can be found at
prb.org
Projections of world population with different estimates for future fertility rates can be found at
undp.org
Other links I found which discuss the issue are
ncpa.org
and
rand.org |
