Falling fertility rates mean nearly every country could have a shrinking population by 2050, a new study has found.
Researchers from the University of Washington estimate that more than three-quarters of countries—155 of the 204 nations included in the study—will not have high enough fertility rates to sustain their population size. This figure will increase to 97 percent of countries by 2100.
While fertility rates will drop in most parts of the world, comparatively high fertility rates in low-income countries will, in contrast, drive population increases in certain regions, predominantly in eastern and western sub-Saharan Africa.
As a result, the world is set to be "demographically divided", with significant economic and societal impacts.
The research was carried out using data on fertility and live births from the Global Burden of Disease, Injuries, and Risk Factors Study 2021.
Baby bust vs baby boom
"We are facing staggering social change through the 21st century. The world will be simultaneously tackling a 'baby boom' in some countries and a 'baby bust' in others," said paper author professor Stein Emil Vollset in a press release.
"As most of the world contends with the serious challenges to the economic growth of a shrinking workforce and how to care for and pay for ageing populations, many of the most resource-limited countries in sub-Saharan Africa will be grappling with how to support the youngest, fastest-growing population on the planet in some of the most politically and economically unstable, heat-stressed, and health system-strained places on earth."
The fertility rate—the average number of children a woman gives birth to—is falling. If the number drops below around 2.1, then the size of the global population begins to drop. Between 1950 and 1955, this figure was around 5.
In South Korea and Serbia, the rate is less than 1.1 child per woman. In contrast, the fertility rate in Chad is 7 per woman, the highest in the world.
By 2100, only six countries and territories are expected to have fertility rates exceeding 2.1 births per woman: Chad, Niger, Samoa, Somalia, Tajikistan, and Tonga. Meanwhile, in Western Europe, the fertility rate is expected to fall from around 1.5 to 1.37 by 2100.
The researchers also predict huge shifts in the global pattern of live births in low-income countries. In 2021, 29 percent of the world's babies were born in sub-Saharan Africa, but this figure is expected to rise to 54 percent of all babies globally by 2100.
Benefits and challenges of falling fertility rates
There are various reasons why fertility rates are falling, according to the researchers. For the most part, however, the shift is being driven by more women being in education and work, as well as greater access to contraception allowing women to choose to have fewer children.
"In many ways, tumbling fertility rates are a success story, reflecting not only better, easily available contraception but also many women choosing to delay or have fewer children, as well as more opportunities for education and employment," said Vollset.
However, for low-income countries with high fertility and population growth, predicted demographic changes will increase the risk of poverty, food insecurity and geopolitical unrest.
For high-income countries, the new fertility predictions emphasize the challenges that come with an ageing population, including the burden on healthcare systems.
Better support for parents
The authors have recommended that better access to contraceptives and female education will help reduce birth rates in higher fertility countries. Meanwhile—in low fertility—higher-income countries, the researchers recommend prioritizing policies that support parents, and open immigration, both of which can help maintain population size and economic growth.
Teresa Castro Martín, a research professor at the Institute of Economics, Geography and Demography of the Spanish National Research Council—who was not involved in the study—commented: "Globally, births will be increasingly concentrated in the areas of the world most vulnerable to climate change, resource scarcity, political instability, poverty and infant mortality.
"Another important contribution is an estimate of the impact that family policies—such as extending parental leave, making nursery schools universal, providing childcare support or facilitating access to assisted reproductive treatment—could have in countries with very low fertility. The impact is estimated to be modest, but could prevent further fertility decline in these societies."
The full findings of the study were published in The Lancet.
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