Analysing fertility trends through Schmertmann's model: Italy and Sweden compared

Alessandra Carioli, Università Bocconi

Postponement of childbearing is a widely addressed issue in fertility literature. Shifts in fertility tempo are seemingly common over centuries but how does it really affect fertility and to what extent? Using age specific fertility rates of Italian and Swedish women, this paper focuses on the presence of fertility postponement in period and cohort outputs and tries to analyse the overall fertility variation. Cohort data have been handled through this method to provide reliable complete fertility outputs also for some recent birth cohorts. In this work I stress the idea and show that postponement of childbearing does not necessarily imply low and lowest-low fertility. The method developed by Carl P. Schmertmann (2003), based upon quadratic spline interpolation, has the clear advantage to study macro data outputs through easily visualized parameters, which help in highlighting when and how postponement occurs and to which extent it affects overall fertility.