lifeexpectancy

Life expectancy is the average number of years a newborn would be expected to live if current mortality rates persist throughout their life. It is most commonly reported as life expectancy at birth, and it can also be estimated for other starting ages, such as life expectancy at age 65. The figure summarizes the overall mortality conditions of a population.

In many countries, life expectancy has risen dramatically over the last century due to improvements in public health, sanitation, vaccination, medical advances, and economic development. However, progress is uneven across regions and populations, reflecting differences in health systems, risk exposures, and social determinants of health.

Life expectancy varies by sex, geography, and socioeconomic factors. Women typically outlive men in most populations. Differences also arise from access to healthcare, education, income, environmental conditions, and lifestyle factors such as smoking, diet, and physical activity, as well as the prevalence of infectious and chronic diseases.

Measurement relies on life tables constructed from demographic and mortality data collected by statistical agencies. Life expectancy is sensitive to recent mortality changes and may shift with new health threats or improvements. It does not predict an individual’s lifespan and does not capture the quality of years lived; healthy life expectancy is a related concept that adjusts for years lived with disability or illness.

Uses include planning for health services, pensions, and retirement policy. International comparisons are made by organizations such as the World Health Organization, World Bank, and United Nations. Limitations include its aggregation across diverse subpopulations and its emphasis on length of life rather than health during those years.