Birth rates in almost all the world’s countries will not be enough to keep their populations stable by the end of the century, according to a major study published today that warns of widening inequalities between rich and poor nations.

“Fertility is falling around the world,” says the report published in the scientific journal The Lancet, which notes that more than half of countries already have fertility rates too low to maintain their population levels.

And “in the future birth rates will continue to decline around the world.”

The report is based on data from the Global Burden of Disease, a project funded by the Bill & Melinda Gates Foundation, and aims to compile data on the health of most countries.

The researchers estimated not only the current birth rates in the countries, but also tried to calculate their future development based on many factors, such as the level of education and child mortality.

They concluded that in 155 countries and territories out of 204 the birth rate by 2050 will not be sufficient to keep their population stable. By 2100, the number of these countries is expected to reach 198, i.e. 97% of the total.

Researchers predict that the population in poor countries will continue to grow for some time, while it will decline in developed countries. Specifically, by the end of the century, most births will be recorded in low- or low- to middle-income countries, with more than half of them occurring in sub-Saharan African countries.

This imbalance risks having “significant effects” on both societies and economies.

By 2021, 110 countries recorded birth rates below the level of 2.1 children per woman needed to keep their population stable.

The report highlights particularly worrying trends in countries such as South Korea and Serbia, where the birth rate is below 1.1 children per woman.

While declining birth rates in richer countries are linked to more opportunities for women in education and work, the researchers point out that there is an urgent need to improve access to modern methods of contraception and education in other poorer regions.

Many of the poorest countries “will struggle to support the world’s youngest and fastest-growing populations in some of the most economically and politically unstable” places, whose health systems are under pressure and affected by extreme heat events, he said. Stein Emil Folstedt of the Institute for Health Metrics and Evaluation (IHME) at the University of Washington in Seattle.

However, the researchers of the World Health Organization expressed their reservations about these predictions.

They criticized several methodological choices of the researchers, underlining in particular that many poor countries currently do not have sufficient data, while underlining that the reduction in fertility can have advantages (in the environment, nutrition…) in addition to disadvantages (in pension systems or the job).