Baby booms, busts, and population ageing in the developed world.

The key challenge facing contemporary society is a process of population ageing rooted mainly in past fertility cycles. The goals of the study reported in this paper were (i) to analyse jointly the post-1930s baby boom and the baby bust that followed, (ii) to consider the specific ways this particular combination influenced the process of ageing in different societies, and (iii) to evaluate some possible implications for policy of different historical experiences. Demographic time series for 27 nations in the developed world were used. The main results confirm the importance of the boom and bust fertility cycle of the second half of the twentieth century for population ageing. Some countries will experience ageing processes driven mainly by the growth of elderly populations while others will age largely as a result of declines in working-age populations. These differences underscore the need to tailor policy priorities for specific patterns of ageing.