For much of human history, population growth was taken for granted. Larger families were common, and each generation was usually bigger than the last. Today, that pattern is changing. Across much of the world, people are having fewer children than ever before.
While headlines often focus on countries such as Japan and South Korea, declining fertility is now a much broader global trend. This story uses United Nations World Population Prospects 2024 data to explore how fertility rates have changed over time and what those changes could mean for ageing populations, population growth and migration.
The first chart shows a major shift over the past seventy years. In the 1950s, the average woman worldwide had around five children. Today, that number is much closer to two. The overall direction is clear: smaller families have become normal across much of the world.
Some countries are not just slightly below replacement level. They are far below it. This means each new generation may become much smaller than the previous one unless migration fills part of the gap.
Falling birth rates do not only affect the number of babies being born today. They also change the age structure of society. Countries with lower fertility often have older populations, which creates new pressure on healthcare, pensions and labour markets.
Population growth is shaped by many things, but fertility remains one of the biggest drivers. Countries with higher fertility are more likely to keep growing, while very low-fertility countries often face slower growth or population decline.
Some low-fertility countries still maintain population growth because migration adds people to the population. For many ageing societies, migration is becoming an important way to support workforce growth and reduce the impact of falling birth rates.
Declining birth rates are often discussed as a future problem, but their effects are already visible today. Many countries are facing ageing populations, changing workforce needs and growing pressure on social support systems.
The data shows that the world is entering a new demographic era. Fewer births may reshape economies, migration debates and the way societies plan for the future.