Modelling Fertility in Modern Populations

Paraskevi Peristera, Athens University of Economics and Business
Anastasia Kostaki, Athens University of Economics and Business

The age-specific fertility pattern has a typical shape common in all human populations and all time periods. In order to describe this pattern several parametric models have been proposed. Recently, the fertility pattern in developed countries exhibits a deviation from the classical one. Recent data sets of United Kingdom, Ireland and United States show distortions in terms of a bulge in fertility rates of younger women. This heterogeneity indicated by the recent fertility distributions of European countries is associated to some extent to marital and non-marital fertility. Additionally in the United States this heterogeneity in fertility patterns may be explained by ethnic differences in the timing and the number of births. As expected, the existing models are unable to describe the new shape of the fertility pattern and therefore the use of more appropriate representations is required. In this paper, a new flexible model for describing both the old and the new pattern of fertility is proposed. In order to evaluate the adequacy of the model, we fit it to a variety of empirical fertility schedules and we reveal that this new pattern of fertility has also arisen in Scandinavian countries while it characterizes and other European countries.