Sub-Replacement Fertility: Why Pure Postponement Models are Inadequate

Elizabeth Sowers, University of California, Irvine
Ron J. Lesthaeghe, University of Michigan and University of California, Irvine

Since the 1960s, Period Total Fertility Rates for Western Europe have fallen to sub-replacement levels. Previous research on the timing of childbirth has estimated the magnitude of the Total Fertility Rate without the birth tempo effect, but the most well known of these models (Bongaarts-Feeney, Kohler& Philipov) do not account for the disparity of “catching up” of childbirth among countries. Using Council of Europe fertility data from 1960 to 2003 for 14 countries, this poster presents a regression analysis that uses 3 factors to predict a country’s PTFR: the Cohort Total Fertility Rate for the cohort born between 1940-1944, the amount of postponed fertility of succeeding cohorts, and the amount of fertility that is eventually “caught up” by these cohorts. The results of this analysis show that considering the recuperation of fertility, as well as fertility postponement, results in substantially more accurate TFR predictions for the countries under consideration.