ABSTRACT
The dynamic character of population growth and its portents have been outlined; it is now necessary to examine, with particular reference to the under-developed lands, those aspects of population that leave the greatest impress upon a country’s economy. The age structure of a population is a factor of the greatest demographic and economic weight. In the first place age distribution conditions birth and death rates in a community while being itself, of course, an intimate expression of them; or in other words, future population growth is related to past trends because of their expression in the age structure. Crude birth rates are expressed as per thousand of the total population, but it is an important refinement to consider the ratio of numbers of births to numbers of women in the reproductive cycle (ages 15–45). Variation in the proportions of women in these age groups will alter the birth rate, assuming that the number of children produced by each woman (fertility) remains the same. Actual age distribution within these (the reproductive cycle) age groups is also important. Women approaching the end of their reproductive period are less fertile than younger women, thus a change in the age distribution of women aged 15–45 will also affect the birth rate: if relatively more women appear in the age group 20–24 than before, other things being equal, the birth rate rises.
