The Institute for Health Metrics and Evaluation (IHME) published in the Lancet has revealed that the fertility rate, which is the average number of children born to a woman in her lifetime, has been declining globally since 1950.

The study projects that this trend of declining fertility rates will continue through the end of the century, resulting in a significant demographic shift.
To maintain stable population numbers, countries need a total fertility rate of 2.1 children per woman, which is known as the replacement level. However, the new analysis estimates that 46% of countries had a fertility rate below replacement level in 2021.
This number is predicted to increase to 97% by 2100, which means that almost all countries in the world will experience a population decline by the end of the century.
A previous analysis by the Institute for Health Metrics and Evaluation (IHME) published in the Lancet in 2020 predicted that the world population will peak in 2064 at around 9.7 billion and then decline to 8.8 billion by 2100.
Another projection by the UN World Population Prospects 2022 predicted that the world population will peak at 10.4 billion in the 2080s.

‘Demographically divided world’

It has been observed that fertility rates are decreasing worldwide, but at varying rates, leading to a change in the global distribution of live births, as per the analysis.
According to study by 2100, the proportion of live births in low-income regions will increase nearly twofold from 18% in 2021 to 35%. Moreover, Sub-Saharan Africa alone will contribute to half of all newborns on Earth by that time.
This shift in the distribution of live births may lead to a "world divided by demographics," with high-income nations grappling with the consequences of an aging population and a shrinking workforce, while low-income regions experience a high birth rate that strains their existing resources, the analysis suggests.

Low fertility in high-income countries

At one end of the spectrum, nations with high incomes and decreasing fertility rates will face the challenge of adapting to an aging population that will place additional pressure on vital systems such as national health insurance, social security programmes, and healthcare infrastructure.
Additionally, labor shortages may become a concern. Conversely, at the other end, low-income countries with increasing live births may encounter difficulties in ensuring adequate resources such as food and water and may find it challenging to improve child mortality rates. These regions may become vulnerable to political instability and security risks.