The world’s population is expected to almost stop growing by the end of this century in a trend unprecedented in modern history, according to new research.

Washington-based think tank The Pew Research Centre has analysed global fertility rates contained in new data from the United Nations.

It found that by 2100, the world’s population is projected to reach approximately 10.9 billion, with annual growth of less than 0.1 per cent – a steep decline from current levels.

Between 1950 and today, the world’s population grew between 1 and 2 per cent each year, with the number of people rising from 2.5 billion to more than 7.7 billion.

The UN’s new ‘World Population Prospects 2019’ report shows that the global fertility rate is expected to be 1.9 births per woman by 2100, down from 2.5 today.

The rate is projected to fall below the replacement fertility rate (2.1 births per woman) by 2070 – this is the number of births per woman needed to maintain a population’s size.

Also, the world’s median age is expected to increase to 42 in 2100, up from the current 31 – and from 24 in 1950, the Pew analysis says.

Between 2020 and 2100, the number of people aged 80 and older is expected to increase from 146 million to 881 million. Starting in 2073, there are projected to be more people ages 65 and older than under age 15 – the first time this will be the case, it says

Contributing factors to the rise in the median age are the increase in life expectancy and falling fertility rates.

Africa is the only world region projected to have strong population growth for the rest of this century. Between 2020 and 2100, Africa’s population is expected to increase from 1.3 billion to 4.3 billion, the Pew analysis says.

Projections show these gains will come mostly in sub-Saharan Africa, which is expected to more than triple in population by 2100. The regions that include the United States and Canada (Northern America) and Australia and New Zealand are projected to grow throughout the rest of the century, too, but at slower rates than Africa.

Europe and Latin America are both expected to have declining populations by 2100. Europe’s population is projected to peak at 748 million in 2021. The Latin America and Caribbean region is expected to surpass Europe in population by 2037 before peaking at 768 million in 2058.

The population of Asia is expected to increase from 4.6 billion in 2020 to 5.3 billion in 2055, then start to decline.

China’s population is expected to peak in 2031, while the populations of Japan and South Korea are projected to decline after 2020. India’s population is expected to grow until 2059, when it will reach 1.7 billion.

Meanwhile, Indonesia – the most populous country in South East Asia – is projected to reach its peak population in 2067.

In North America, migration from the rest of the world is expected to be the primary driver of continued population growth with the immigrant population in the United States set to see a net increase of 85 million over the next 80 years, according to the UN projections which place it roughly equal to the total of the next nine highest countries combined.

In Canada, migration is likely to be a key driver of growth, as Canadian deaths are expected to outnumber births.

Six countries are projected to account for more than half of the world’s population growth through the end of this century, and five are in Africa.

The global population is expected to grow by about 3.1 billion people between 2020 and 2100. More than half of this increase is projected to come from Nigeria, the Democratic Republic of the Congo, Tanzania, Ethiopia and Angola, along with one non-African country (Pakistan). Five African countries are projected to be in the world’s top 10 countries by population by 2100.

India is projected to surpass China as the world’s most populous country by 2027. Meanwhile, Nigeria will surpass the US as the third-largest country in the world in 2047, according to the projections, the Pew analysis says.

Between 2020 and 2100, 90 countries are expected to lose population. Two-thirds of all countries and territories in Europe (32 of 48) are expected to lose population by 2100.

In Latin America and the Caribbean, half of the region’s 50 countries’ populations are expected to shrink. Between 1950 and 2020, by contrast, only six countries in the world lost population, due to much higher fertility rates and a relatively younger population in past decades.

Africa is projected to overtake Asia in births by 2060. Half of babies born worldwide are expected to be born in Africa by 2100, up from three-in-ten today.

Nigeria is expected to have 864 million births between 2020 and 2100, the most of any African country. The number of births in Nigeria is projected to exceed those in China by 2070.

Meanwhile, roughly a third of the world’s babies are projected to be born in Asia by the end of this century, down from about half today and from a peak of 65 per cent in the 1965-70 period.