Population Heterogeneity in the Number of Children Born: Is There a “Parity Transition”?

Abstract

The paper studies the dynamics of fertility heterogeneity in terms of parities in the countries with a birth rate below replacement for cohorts of women born in 1960-1980 or earlier. Fertility heterogeneity is estimated using the distribution of women by birth order, the probabilities of having children of certain orders, and three fertility concentration indices. Empirically, the study bases on the Human Fertility Database data for 18 countries.

The authors show the existence of the so-called “parity transition”, which contains two stages, namely, a gradual decrease and subsequent increase in fertility heterogeneity in terms of parities. The study regards the contribution of different parities in the changes in heterogeneity that occur at these stages. Examination of data for five countries with a long period of observation showed that the first stage may be associated with a decrease in high-parity births, while the second stage is characterized by an increase in childlessness rate. The authors note that in the future this conclusion should be supported by a larger number of observations.

The study confirms the presence of the “Eastern European” and the “Western European” fertility models in the context of the population heterogeneity dynamics measured by the number of children born. The “Eastern European” fertility model remains even in the process of growing parity heterogeneity observed for the generations born in the second half of the 1970s. Its important feature is the relatively low level of fertility heterogeneity in terms of different parities, as well as less significant changes in fertility concentration in the process of “parity transition”.

Acknowledgments. The authors are grateful to two anonymous reviewers whose comments allowed us to significantly improve the text.

The research was conducted with the fi­nancial support of the  Government research subsidy No. 122041800047­ 9 “The reproduction of the population in the context of the socio­economic development”.