expectancy Health life expectancy is the expected number of years of life remaining at a given age. It is a statistical measure used by public health and demographers to quantify the impact of health on longevity. In the developed world, health life expectancy at birth is now over 80 years on average – a dramatic increase from just over 50 years in 1950. This increase is largely due to advances in medical science and public health, and has resulted in people living longer and healthier lives.