The Second Mortality Transition: A New Look at Long Term Trends in Mortality Decline

Demographic transitions occur in stages. We argue that there have been two mortality transitions, and that the European and European-overseas countries for which reliable long-term mortality data exist completed the first stage of the mortality transition around the middle of the twentieth century. In the first stage, or First Mortality Transition (FMT), from the nineteenth to the middle of the twentieth century, mortality decline occurred mainly at younger ages, survivorship to age 50 increased, and there was a secular growth in the rate of ageing (the rate of mortality increase) over and above that due to the decline in the mortality rate at age 50. By 1950, however, this transition was more or less complte, and the underlying level of survivorship to age 50 began to stabilise. In the Second Mortality Transition (SMT) the main weight of mortality decline thus shifted to older ages, above age 50, and the secular trend in the rate of ageing now shifted from positive to negative, offsetting the continuing decline in the rate of mortality at age 50. There are important differences between countries in the patterning of these changes, and in particular, the patterns differ for males and for females. However, the changes over time have been identical for both sexes. Analysis of country-level variations, by sex, will enable us to understand further the reasons for this shift from the First to the Second Mortality Transition and the differences in the pace at which it has occurred.