When fertility rates plummeted below 1.3 children per woman in parts of Europe during the 1990s, demographers coined a term to capture what seemed like an alarming new demographic phenomenon: “lowest-low fertility.” The label stuck. Today, media headlines regularly invoke fears of a “demographic winter” or even human extinction as more countries cross this threshold. But does grouping all these countries together under one label still make sense? Our new paper in Population and Development Review suggests it’s time to retire this concept.
The world of lowest-low fertility has changed dramatically since the term was introduced. In 2000, it was largely a European story, concentrated in post-socialist Eastern Europe and parts of Southern Europe, affecting about 344 million people. Fast forward to today, and lowest-low fertility has gone global—spanning every continent from Canada to Colombia, Thailand to Mauritius, affecting more than 2 billion people. But here’s the problem: calling all these places “lowest-low” obscures more than it reveals.
Consider two countries both labeled as having “lowest-low fertility”: South Korea, with a total fertility rate of 0.72, and Canada, at 1.26. Both fall below the 1.3 threshold, so conventional wisdom might suggest they face similar demographic futures. Yet official projections tell radically different stories. South Korea’s population is forecast to decline by 27% by 2070 even under optimistic scenarios, with nearly half the population aged 65 and older. Canada, meanwhile, is projected to grow by over 40% during the same period. How can two “lowest-low” countries have such divergent trajectories?
The answer lies in what the fertility label ignores: migration, mortality, age structure, and a host of socioeconomic factors. Canada’s sustained immigration transforms its demographic equation entirely—by 2070, immigration is projected to exceed births. South Korea, with minimal immigration and already rapid aging, faces a very different reality. Meanwhile, territories like Hong Kong, Macao, and Singapore have maintained very low fertility for decades while sustaining population growth through migration. And in many Eastern European countries, high mortality rates compound the effects of low fertility in ways the label doesn’t capture.
The range of what counts as “lowest-low” has also expanded dramatically. In 2000, the category spanned just 0.17 children (from 1.13 to 1.30). Today it spans 0.62 children (from Macao’s 0.66 to Finland’s 1.28). Grouping societies across such a wide range under a single classification is like calling everything below room temperature “cold”—it conflates fundamentally different conditions.
There’s another layer of complexity: timing. Some Latin American countries recently entering the lowest-low category are still in the middle of a “postponement transition”—women are delaying childbearing to later ages. As this transition completes, fertility could partially rebound, as happened in parts of Eastern Europe. But countries like South Korea or Spain, where women’s mean age at first birth already exceeds 30, have exhausted this demographic margin. Their low fertility reflects something more fundamental than calendrical shifts.
Perhaps most importantly, focusing primarily on fertility rates distracts from potentially more effective policy responses. Recent research shows that in Eastern Europe, investments in reducing preventable mortality would be more effective at slowing population decline than policies aimed at raising fertility to replacement level. Similarly, studies demonstrate that increasing labor force participation, improving education, and better integration of migrants can do more to reduce economic dependency than simply boosting birth rates.
None of this means fertility doesn’t matter. But the “lowest-low” framework encourages a kind of fertility-centric determinism that overlooks how migration, mortality, human capital, and institutional factors shape demographic futures. It sustains alarm where nuance is needed, potentially driving ineffective pronatalist policies while diverting attention from more impactful interventions.
What would replace this framework? We advocate for a multidimensional approach to demography—one that recognizes fertility as one component within a broader system. This means assessing migration patterns (which can make replacement-level fertility substantially below 2.1), considering mortality reduction as a demographic lever, evaluating human capital and labor market dynamics, and understanding how institutions enable or constrain reproductive choices.
The core issue isn’t the fertility numbers themselves but the structural conditions that shape demographic behavior and outcomes. A territory with a TFR of 0.7, minimal migration, high preventable mortality, and an already super-aged population faces fundamentally different challenges than one with a TFR of 1.3, sustained immigration, excellent health outcomes, and a younger age structure. Calling both “lowest-low” doesn’t help us understand their distinct realities or design appropriate responses. Nearly 25 years after its introduction, it is time to move beyond the threshold and toward a more integrated understanding of how demographic, social, and economic factors interact. Only then can we design a diverse portfolio of policies that address the challenges and opportunities of demographic change.
About the Authors
Stuart Gietel-Basten, The Hong Kong University of Science and Technology
Ignacio Pardo, Universidad de la República