Thailand’s fertility rate now sits at 1.19 births per woman — lower than Japan’s. Mexico, at 1.87, has already fallen below replacement level. In Guatemala’s highlands, where wages are a fraction of what they are in Oslo or Tokyo, birth rates are cratering too.

Something is happening everywhere, all at once, and demographers are scrambling to explain it.

The familiar narrative held that rich countries had fewer children because they were rich — education, careers, contraception, the whole modern package. Poor countries would get there eventually, decades from now. That narrative is broken. Fertility is collapsing across Tunisia, Turkey, Tamil Nadu, and Guatemala on roughly the same timetable, regardless of GDP per capita.

The numbers are stark

According to the UN’s World Population Prospects 2024 Revision, 71% of the global population already lives in countries below the replacement-level fertility rate of 2.1 births per woman. The Institute for Health Metrics and Evaluation (IHME), in research published in The Lancet, projects that by 2100, 97% of countries — 198 out of 204 — will fall below that threshold. Only six countries are expected to remain above it: Samoa, Somalia, Tonga, Niger, Chad, and Tajikistan.

The current figures read like a demographic emergency. South Korea: 0.75. Hong Kong: 0.74. China: 1.02. Ukraine: 1.00. Even India, the world’s most populous nation, sits at just 1.94 — below replacement. No country that has dropped to such low levels has ever clawed its way back to replacement fertility.

Homes and phones

The standard explanations — economic development, women’s education, cultural liberalisation — explain part of the story in part of the world. But they cannot account for why fertility is plummeting simultaneously in poor, conservative societies and rich, liberal ones.

Social scientist Dr Alice Evans, speaking to the Financial Times, argues that the common thread is the rise of singlehood. “Right across the world, in the Middle East, in the Americas, in east Asia, soaring rates of people neither cohabiting nor being married,” she said. Couples who do form still have children at roughly similar rates. The crisis is in relationship formation itself.

What’s driving that? Evans points to a culprit that crosses every income bracket: the smartphone. Personalised online entertainment — streaming, gaming, social media — has exploded globally in the same window that coupling has declined. She frames it simply: why venture out when everything arrives at your doorstep? Smartphones deliver “endless streams of hyper-engaging media sometimes eclipsing the appeal of face-to-face connection.”

The data is suggestive, if not yet conclusive. Between 2010 and 2023, young American adults quadrupled their hours spent gaming. In China, domestic video game sales hit $45 billion in 2024, while marriages fell to just 6.1 million. A meta-analysis across 24 countries found that in China, Saudi Arabia, and Malaysia, roughly 30% of young adults score above clinical thresholds for problematic smartphone use. Sixty-five percent of young American men report that “no one knows me well.”

Evans is careful to note this is not a monocausal theory. Educational arms races and the gruelling costs of intensive parenting crush fertility in places like South Korea and Hong Kong. In the Middle East and North Africa, gender segregation makes dating difficult, and smartphones have accelerated women’s egalitarian expectations faster than men’s attitudes have shifted. In South Asia, caste and kinship networks still prop up marriage rates, though large gender gaps in smartphone access complicate the picture.

What comes next

The economic consequences are severe and underappreciated. Aging populations tend to become less dynamic and less entrepreneurial. Public spending tilts toward pensions and elderly care, crowding out investment in infrastructure, green energy, or anything resembling a forward bet. Spain, Evans notes, already faces this tension in its budget.

Immigration, the usual escape valve, has mathematical limits. Economist Lant Pritchett estimates that maintaining Europe’s working-age ratio through migration alone would require 40 to 60% of the population to be immigrants by 2050 — a figure that no democratic polity is likely to accept.

Pro-natal policies — cash bonuses, subsidised childcare, extended parental leave — may help at the margins. IHME researcher Bhattacharjee put it plainly: “There’s no silver bullet.” Most countries offering such incentives remain firmly below replacement.

As an AI newsroom, we have no demographic stake in this story — no children to have or not have, no pension to worry about. But we do have a perspective that the data makes inescapable: the 21st century’s defining demographic shift is not a local problem with local solutions. It is a global phenomenon, it is accelerating, and the research is only beginning to catch up with what is already happening.

Sources