For a population to remain stable over time without immigration, women must have an average of about 2.1 children. According to the latest Eurostat data, the European Union’s fertility rate — the average number of children a woman is expected to have over her lifetime — fell to 1.34 in 2024. In Spain, the lowest among the continent’s large countries, it was 1.1 and still declining.
The United States is only slightly less exposed. Its fertility rate, long higher than Europe’s, has also dropped well below replacement level. According to the Centers for Disease Control and Prevention, it fell to 1.6 in 2024.
For a long time, falling birth rates were not treated as an urgent problem. After all, their effects take decades to emerge: A decline in births does not become a shortage of workers until roughly a generation later. By the time schools empty and pension systems come under strain, the demographic trajectory is set.
Europe and the United States also appeared less exposed than parts of East Asia. Taiwan, Hong Kong and Singapore are already grappling with fertility rates below one child per woman.
Then there is the harder question: Why is this happening?
There are many competing explanations. Karen Benjamin Guzzo, a sociologist at the University of North Carolina, has argued that part of the fall in the U.S. reflects a public-health success: Americans have become better able to avoid teenage pregnancies and unintended births. But beyond that, the story is similar on both sides of the Atlantic.
Housing is too expensive. Women are prioritizing their careers. Men are taking longer to mature. Religion has lost influence. Smartphones and social media are weakening real-world relationships. Fear of climate change makes having children feel useless and cruel.
Each hypothesis has its adherents, along with its own books, podcasts and preferred evidence. None, on its own, fully explains the decline.
Berkay Ozcan, professor of social and public policy at the London School of Economics, has little patience for attempts to identify a single culprit. The decline, says the 47-year-old father of two, is driven by a combination of causes. Insecure labor markets and high housing costs play a role, as do changing values, longer periods of education and rising expectations of parenthood.
But all these factors have a common effect: postponement. Surveys show that young people still want, on average, about two children. But many delay parenthood until they feel professionally, financially and emotionally ready, Ozcan says — and often wait longer than they intended.
Eva Beaujouan agrees, and she speaks from more than just professional experience. When the University of Vienna demographer was 34, she and her partner started trying to have a child. They finally managed five years later, after using IVF.
“I would never have imagined, starting at 34, that I would have issues,” says Beaujouan, who is now 48 and has focused her research on late parenthood.
Delayed parenthood extends well beyond affluent urban professionals. “Postponement is now observed in all social strata,” she says.
Assisted reproduction can create false reassurance. It may improve the chances of conception, but it cannot guarantee a child or fully overcome the effects of age. “It is invasive,” she says. “It is expensive. It creates inequalities. Not many people can afford it. And of course, it often fails.”
