The proportion of adolescents in the global population peaked around 1980 and is now on the decline almost everywhere, a trend expected to continue through 2050. The absolute number of adolescents, however, is expected to rise during that same period.
More than half of all adolescents globally live in Asia. In absolute numbers, South Asia is home to more adolescents – around 340 million – than any other region. It is followed by East Asia and the Pacific with around 277 million. The adolescent population of either of these regions dwarfs that of any other region in the world.
Despite this, sub-Saharan Africa is the region where adolescents make up the greatest proportion of the population, with fully 23 per cent of the region’s population aged 10–19.
The striking differences among regions in the proportion of adolescent populations result from a demographic transition that occurs when declines in mortality rates are later followed by declines in fertility rates; the interim period of lower mortality rates and still-high fertility rates results in a large proportion of youth in a population, sometimes termed a ‘youth bulge’. Once fertility starts declining, a favorable age structure can be created in these countries/regions with a growing working age population and fewer dependents. If the right investments are made in time in adolescents and youth, these countries/regions can realize the enormous opportunity that this population dynamic represents. However, not every country has experienced declining fertility rates yet to create favorable age structures and/or population dynamics.