India is set to overtake China as the most populous country by 2027 and will have almost 1.64 billion inhabitants by 2050, says a United Nations report. It further adds South Asia’s opportunity to reap the “demographic dividend” will peak by 2047. Globally, people aged above 65 are the fastest growing age group, putting pressure on social protection systems as the proportion of the working-age population shrinks.

According to the World Population Prospects 2019 report, India is expected to add 273 million people by 2050, which will be the largest national increase in the world. China, on the other hand, is expected to become smaller, dropping from its current 1.43 billion people to approximately 1.4 billion by 2050.

The rate of population growth is the highest in sub-Saharan Africa, where the fertility rate stand at 4.6 births per woman over a lifetime. The region is expected to double its population by mid-century. Nigeria is expected to add 200 million people over the next three decades and overtake the U.S. to become the third most populous nation.

Globally, it’s the post-working-age group that is growing the fastest. By 2050, one in six people will be above 65, compared with one in 11 people in 2019. In 2018, for the first time in history, people above 65 outnumbered children under five years of age. By 2050, the number of people over 80 is expected to triple to 426 million.

This trend has also led to falling proportions of working-age people to support an ageing population. By 2050, almost 50 countries are expected to have less than two working-age people to support every person above 65.