A recent study published in The Lancet has projected a significant decline in fertility rates across the globe, with 76% of countries and territories expected to fall below population replacement levels by 2050, increasing to 97% by 2100. This trend suggests a divide between "baby boom" and "baby bust" scenarios, with low-income countries experiencing the boom, mainly in sub-Saharan Africa, while high-income countries face declining birth rates.

The research, based on data collected from 1950 to 2021, indicates a shift towards over three-quarters of live births occurring in low- and lower-middle-income countries by the end of the century. Notably, the global fertility rate has decreased from 5 children per woman in 1950 to 2.2 in 2021, with 54% of countries already below the replacement rate of 2.1 children per woman by 2021.

Countries with extremely low fertility rates, such as South Korea and Serbia, are highlighted as facing challenges associated with a shrinking workforce. Furthermore, resource-limited countries are expected to grapple with supporting rapidly growing populations amidst political, economic, and health system strains.

The decline in fertility rates in high-income countries is attributed to increased opportunities for women in education and employment, emphasizing the need for better access to contraception and female education globally. The authors suggest that as populations shrink, reliance on immigration will become essential for sustaining economic growth.

However, the study acknowledges limitations due to data quality, particularly concerning the COVID-19 pandemic period.