The Demographic Drivers of Population Ageing: A Decomposition of Central and Eastern Europe, 1990–2025

Population ageing is one of the most pressing demographic challenges, yet its main drivers remain contested. A key limitation of existing research is that the initial age structure is rarely treated as a separate driver, despite its influence on the pace and pattern of ageing. This study adapts a decomposition method based on the stationary population model to identify the separate contributions of fertility, mortality, net migration, and the initial age structure to changes in mean age. We apply this framework to Central and Eastern Europe, a region that has lost its earlier advantage of having a relatively young age structure compared with the rest of Europe. The results show that below-replacement fertility accounted for about half of the increase in mean age between 1990 and 2025. One of our main findings is that the contribution of the initial age structure exceeded the combined effect of mortality improvement and net migration. However, the latter showed substantial country-level variation. It also revealed the double burden of outmigration, as in countries affected by severe net outflows, it reduces population size while also accelerating ageing. The findings further indicate that the initial age structure was the main channel through which convergence in population ageing emerged in the region. Finally, cluster analysis identifies distinct groups of countries according to similarities in the demographic forces shaping their ageing processes.