Same outcome, different narratives. A comparative microsimulation study of fertility change in Bulgaria, Poland and Russia

Dora Kostova, Max Planck Institute for Demographic Research
Marta Styrc, Warsaw School of Economics
Martin Spielauer, International Institute for Applied Systems Analysis (IIASA)

Before the political and economic transition at the end of the 1980s, Bulgaria, Poland and Russia showed very similar and remarkably stable demographic patterns characterized by early and universal marriage and fertility around the replacement level. This era of demographic stability was followed by a sharp drop of period fertility reaching its lowest point at the end of the millennium. While this experience was shared by all three countries, the behavioral changes leading to the fertility decline followed very distinct patterns. The aim of this study is to quantify the individual contributions of the various changes in union formation, union stability, and fertility risks in different life-course constellations to the overall drop in fertility. For this end we have developed a microsimulation model based on event history models estimated from the 2004 Bulgarian and Russian Generations and Gender Surveys and the 2002 Polish Fertility Survey. The results indicate that the postponement of first union formations is the main driver of the fertility decline in Bulgaria. This change is almost absent in Poland where the drop of fertility is predominantly an effect of declining first birth intensities within unions. In Russia on the contrary, it is the decrease of the second birth hazard which contributes most to the drop in fertility. Interestingly, the steep increase of union dissolution risks observed in Russia has no effect on fertility: the low second birth risk within the same union is compensated by the new partner effect.