In 1970, the average woman in Mexico could expect to have seven children. By 2014, that figure had dropped to around two. Today, it stands at just 1.6 — a number far below the replacement rate of 2.1, meaning the population is no longer sustaining itself. Mexico is far from an outlier. Across the globe, fertility rates are plunging, and researchers are warning of profound social, economic and political consequences.
As reported in Nature, the Institute for Health Metrics and Evaluation (IHME) at the University of Washington projects that by 2050, more than three-quarters of countries will have fertility levels below replacement. “There has been an absolutely incredible drop in fertility — much faster than anyone had anticipated,” said Jesús Fernández-Villaverde, an economist at the University of Pennsylvania. “And it is happening in a lot of countries you would have never guessed.”
The numbers are stark. In the mid-twentieth century, the global fertility rate averaged five children per woman. By 2023, it had fallen to 2.2. About half of countries are now below the replacement threshold, and in some nations the decline has been extreme. South Korea’s fertility rate, for instance, has fallen from 4.5 in 1970 to just 0.75 in 2024, with its population already shrinking. Demographers generally agree that the world’s population will peak within the next 30 to 60 years before entering a long-term decline — the first such contraction since the Black Death in the fourteenth century. The United Nations suggests China’s population has already peaked at 1.4 billion, while India is expected to reach its peak around the 2060s. Sub-Saharan Africa is the major exception: with fertility rates still high, the region is projected to account for more than half of all global births by 2100.
The factors driving fertility decline are numerous and complex. Increased access to contraception and reproductive healthcare has given women greater control over childbearing. Expanding education and career opportunities, particularly for women, have shifted family planning choices. Economic pressures, such as the soaring costs of housing, childcare and education, discourage many from having larger families. Social dynamics also play a role, with younger generations forming fewer partnerships, postponing marriage and childbearing, or choosing to remain child-free. In some societies, cultural movements are reinforcing this trend — South Korea’s Four Nos feminist movement, for example, rejects dating, marriage, sex and childbirth altogether. At the same time, medical and biological concerns, such as declining sperm counts potentially linked to environmental toxins, add further complexity. Many would-be parents also cite political instability, climate change and economic insecurity as reasons for delaying or avoiding children.
The consequences of this global “baby bust” are uncertain but potentially far-reaching. Economies long reliant on population growth may face slowing innovation, shrinking workforces and increased fiscal pressure as fewer working-age citizens are left to support growing numbers of elderly people. Nature notes that ripple effects could extend into geopolitics, weakening military power and diminishing the influence of nations with declining populations. Fewer workers may also mean slower adoption of green technologies, hindering global climate goals.
Governments have begun experimenting with policies aimed at reversing fertility decline. Cash incentives, tax breaks and so-called baby bonuses have yielded only modest, short-term results. Nordic nations that pioneered generous parental leave, subsidized childcare and policies encouraging fathers to take part in parenting have fared somewhat better, with slower declines than other parts of Europe. But even there, birth rates continue to fall. Many researchers now argue that instead of chasing full reversal, nations should focus on building resilience — adapting societies to a future with fewer children and more elderly citizens.
Adaptation strategies could include strengthening care systems, expanding eldercare and raising retirement ages, which some countries are already doing. According to data cited by Nature, a 70-year-old today has roughly the same cognitive abilities as a 53-year-old did in 2000, making longer working lives increasingly feasible. Immigration is another potential solution, helping to fill labor shortages in wealthier nations while providing opportunities for people from regions with higher fertility. Yet migration remains politically sensitive, often fueling tensions rather than easing them.
Despite the challenges, experts see potential silver linings. A smaller global population could ease environmental pressures and allow societies to invest more in each individual through education, healthcare and innovation. Stuart Gietel-Basten, a sociologist at the Hong Kong University of Science and Technology, emphasizes that declining fertility “is only a disaster if you don’t adapt.” Barbara Katz Rothman, a sociologist at the City University of New York, adds that humanity is not on the brink of extinction, remarking: “We’re not not making babies. The human race is not folding in on itself.”
As Nature underscores, the world is entering uncharted demographic territory. While the global fertility decline raises valid concerns about economic stability, geopolitical influence and generational balance, it also presents an opportunity to reshape societies in more equitable and sustainable ways. The challenge for governments will not simply be to encourage people to have more children, but to ensure that systems can adapt to a new demographic reality — one in which resilience may matter more than growth.
