More than half the growth we will see in the next 30 years will happen in just eight countries - the Democratic Republic of the Congo, Egypt, Ethiopia, India, Nigeria, Pakistan, the Philippines and Tanzania.

At the same time, some of the world's most developed economies are already seeing population decline as fertility rates fall below 2.1 children per woman, which is known as the "replacement rate". In 61 countries, the report says, populations will decline by at least 1% by 2050.

With one of the lowest fertility rates in the world (at 1.15 children per woman), China has announced that its population is due to start declining next year - much earlier than previously thought. That is despite the country abandoning its one child policy in 2016 and introducing incentives for couples to have two or more children.

As India's population continues to grow it will almost certainly overtake China as the country with the biggest population in the world.

Fertility rates are falling globally - even in many of the countries where the population is expanding. That is because, as previous generations expand, there are more people having children, even if individually those people are having fewer children than their parents did.

Growth is also largely thanks to developments in medicine and science which mean that more children are surviving into adulthood and more adults into old age. That pattern is likely to continue, which means that by 2050 the global average life expectancy will be around 77.2 years.

But this pattern means that the share of the global population aged 65 years or above is projected to rise from 10% this year to 16% in 2050. Again the distribution will be unequal with some countries, in East Asia and Western Europe, already seeing more extremes in ageing.

The global population is growing at its slowest rate since 1950, having fallen under one per cent in 2020, it said.

The world's two most populous regions in 2022 were Eastern and Southeastern Asia, with 2.3 billion people, representing 29 per cent of the global population; and Central and Southern Asia, with 2.1 billion, representing 26 per cent of the total world population.

China and India accounted for the largest populations in these regions, with more than 1.4 billion each in 2022.

More than half of the projected increase in global population up to 2050 will be concentrated in just eight countries: the Democratic Republic of the Congo, Egypt, Ethiopia, India, Nigeria, Pakistan, the Philippines and Tanzania.

Pakistan, the UN projects, will be the fifth most populous country in 2022.

The report estimated that 10 countries experienced a net outflow of more than 1 million migrants between 2010 and 2021.

In many of these countries, these outflows were due to temporary labour movements. For instance, Pakistan witnessed net outflow of -16.5 million during 2010-2021; India (-3.5 million); Bangladesh (-2.9 million); Nepal (-1.6 million); and Sri Lanka (-1 million).

World’s population projected to touch eight billion by mid-November 2022: UN report Implications for development

* Bigger the country’s population, greater the number of people it has to support

* People’s productivity will have to increase

* Proportion of working-age people in total population will be critical

* India has higher proportion of working-age people than China: Former chief statistician Pronab Sen

* Will need policies to increase jobs so that labour force participation rate increases for both men and women