The crossover between life expectancies and their record values

Vladimir Canudas-Romo, Johns Hopkins University
Michal Engelman, Johns Hopkins University

Historically, the expectation of life at age one (e1) has exceeded the expectation of life at birth (e0). The crossover between e0 and e1 only occurred in the second half of the twentieth century in the developed world. The timing of this crossover is when infant mortality is equal to the inverse of life expectancy at age one. This simple relation divides the world into countries that have achieved the crossover in life expectancies, e0 and e1, and those that have not. The international comparison of life expectancies at different ages allows us to calculate the record maximum life expectancy (RMLE) time trend. The convergence of the RMLE to the record e0 demonstrates the process over time whereby mortality between ages one and five declined before mortality in the first year of life, followed by a second phase of decline where mortality in infancy declined faster than in the later childhood years.