The recent transformation of the fertility pattern in developed countries: Description and forecasting

The fertility curve has traditionally shown a bell-shaped pattern common in all human populations and all time periods. However recently, the fertility pattern of some developed populations exhibits a clear transition from its classical shape to a more complicated one in terms of a distortion in early ages. This heterogeneity might be associated to some extent to marital and non-marital fertility. Additionally in the USA this heterogeneity might be attributed to ethnic differences in fertility behavior. In this work a flexible parametric model adequate for describing both the old and the new shape of the fertility curve is fitted to the age-specific fertility rates of the total population of the UK and the USA for each single year during the last twenty year period. Then in order to examine the development of the fertility curve through time, the evolution of the parameter values is each population is considered. Finally in order to examine the hypothesis of racial heterogeneity of fertility behavior, the model is fitted to age-specific fertility rates of the USA of the three major ethnic groups and to age-specific fertility rates of the UK of married and unmarried women.