Implications of recent fertility trends in less developed countries for world population projections.

This paper argues that demographers must reexamine their assumptions and methodologies for making world population projections because the majority of the population of the less developed countries have recently entered a phase of moderately rapid fertility decline. The paper has 4 sections: 1) a review of the evidence for fertility decline in LDCs; 2) a review of research on the causal factors in fertility decline; 3) a discussion of the implications of these findings for future projections of world population, and development of an appropriate set of assumptions for new projections; and 4) a summary of the results of application of the new assumptions to projection of future world population. The authors contend that between 1968 and 1975 the average family size throughout the world declined by 12%, from 4.6 to 4.1 births per woman, and that 90% of the population of less developed nations lived in countries which experienced a measurable fertility decline. They conclude that the major cause of the unexpected fertility decline between 1968 and 1975 was the amount of effort expended on family planning programs, and further that fertility decline in the remainder of this century will be determined almost as much by the amount of family planning effort as by the amount of other socioeconomic development. Criticisms of their work by other demographers are cited and discussed.