Age at First Birth and Completed Fertility across the 1940s–1970s Birth Cohorts

Krystof Zeman , Vienna Institute of Demography
Eva Beaujouan, University of Vienna (Wittgenstein Centre)
Mathias Nathan, Programa de Población, Facultad de Ciencias Sociales, Universidad de la República

The rise in age at first birth has been universal across the low fertility countries over the last decades. In parallel, cohort fertility levels have tended to decrease, but they stagnated or even experienced a slight rise in a small set of countries in the most recent birth cohorts. Using large-scale surveys, census data and published data from a range of low-fertility countries of different regions (Austria, Switzerland, Great Britain, France, Spain, Italy, Sweden, Uruguay, and USA), we investigate the relationship between age at first birth and mother’s completed cohort fertility conditional on age at first birth across the 1940s–1970s birth cohorts, and study how it may have shaped the overall change in total cohort fertility levels. We observe that in a few countries and cohorts, completed fertility among later-starting mothers increased, reflecting a “catch up” effect among those who had postponed childbearing. However, in the majority of examined countries and cohorts the relationship between age at first birth and mothers’ completed fertility remained almost unchanged. Such stability is striking in cohorts where many other family behaviours were changing and mean ages at first birth increased by around 4 years. To quantify the contribution of changes in age at first birth to overall change in cohort fertility across birth cohorts, we will rely on a decomposition analysis that will also take into account trends in childlessness and mothers’ completed fertility conditional on age at first birth.

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 Presented in Session 127. Fertility Timing