Population growth forecasts often refer to total fertility rate, which refers to the average number of children born per woman. Countries generally maintain stable populations with a TFR around 2. According to the Central Intelligence Agency, 40 countries have a TFR above 4, and seven have a TFR above 6. All of the countries with high fertility ratings suffer from low per capita income levels and high rates of poverty. Many of the high fertility countries are in Africa, where population has nearly tripled since 1960.
The high birth rates in poor countries highlights the link between economic insecurity and population growth. In the countries with the highest birth rates, child mortality is high. At the same time, children become economically productive at an early age, particularly in agrarian societies, contributing to the overall welfare of the family. Children also provide security as the parents age. In poor societies, most elderly people must rely entirely on family for economic support. When child mortality rates are high, it become imperative to have a larger number of children to ensure that some reach adulthood. Many cultures also emphasize the importance of bearing several male children.
U.N. statistics show a strong correlation between female education and reduction of child mortality rates, with an estimated 5 percent to 10 percent mortality reduction for every year of school. From this it can be inferred that gender inequality is a major contributor to rapid population growth.
Although mortality rates remain high in the poorest countries, worldwide rates consistently dropped in all socioeconomic categories during the second half of the 20th century. While high birth rates represent the biggest factor in rapid population growth, reduced mortality rates also contribute. According to the United Nations, all regions of the world except sub-Saharan Africa and Oceania reduced child mortality by more than 50 percent between 1990 and 2009. While improved mortality figures may increase population in the short term, it is worth noting that sub-Saharan Africa contains many of the countries with the highest fertility rates in the world. In the long term, reduced mortality rates are more likely to cause a slowing of population growth.