Fertility choices are so closely related to economic factors that researchers have faced great difficulties in distinguishing exactly how changes in one affect the other. For example, people with higher income tend to have fewer children than people with lower income. Is this because having more income reduces the desire to have children; or is it because having a smaller number of children raises income by allowing more time to earn it? Or could it be because lower-income people in some countries cannot afford or do not have ready access to family planning methods?
Research hasn't been able to show that rapid population growth causes poverty, but we see across all developing countries over time a strong inverse relationship between fertility and per capita income, and fertility and life expectancy - two very common indicators of well-being. There is also a clear connection between high fertility and poverty and the formation of a trap in which low incomes may exacerbate high fertility rates and vice versa.
These traps are plausibly caused by the poor health (high infant and maternal mortality, high infectious diseases rates, and inadequate public health services) and poor living standards (poor employment opportunities, malnutrition, low rates of educational achievement) that exist in these countries. High fertility is a common element among them but it is virtually impossible to sort out how much the poverty and low life expectancy traps are caused by high fertility, or create high fertility. Policies in these countries must strive to break the cycles that create poverty and low life-expectancy traps.
Demographics and Poverty will be the focus of our February 2009 lecture, Population Growth and Poverty in the Developing World Revisited, by CGD president Nancy Birdsall. For current information on lecture dates, times and locations, and to RSVP, see the Lecture Series Overview. **This event has been postponed. Please check back soon for more details.**