The population pyramids I compared are Haiti (an LDC) and Ireland (a MDC). As can be seen, Haiti has a much younger population than Ireland. This follows the trend observed between LDC's and MDC's.
Haiti is officially the poorest country in the Western Hemisphere, ranking 148 of 179 on the Human Development Index. Meanwhile, Ireland ranks 5 out of 179 on the HDI, and is relatively wealthy. The total fertility rate for each Irish woman sits at 2.0, keeping the Irish population relatively stable. Haitian women, on the other hand, average 4.0 births in their lifetime, a full 2.0 children per woman higher than Ireland.
There are several factors that contribute to this trend. It is likely that most Irish women have demanding careers throughout their childbearing years. Because of this, and the wide availability and practice of birth control methods in Europe, Irish couples limit the size of their families to cater to their desires. Hatian women can not afford luxuries such as these, and have characteristically larger families. In the slums of Haiti, women are usually not a part of the workforce. Instead, they spend time caring for their children. Children in 3rd world countries can aid the family's survival by becoming a source of work and income.
As far as can be determined, the Irish population will continue to grow older and live longer, while the population of Haiti will remain young with children constituting the most significant portion of the population.
-Daniel Uden 1-29-2009