Fertility
Total fertility rate (births per woman), historical and projected, against the replacement-level reference of roughly 2.1.
Global fertility trend, 1950–2100
Current TFR ≈ 2.2 births per woman
What the data show
The global total fertility rate has fallen to about 2.2 births per woman in 2024, well below the replacement level of roughly 2.1, and is projected to continue declining under the UN medium variant.
Why it matters for continuity
Fertility shapes the size of the next generation, but a single number does not determine population growth — cohort size, mortality, migration and demographic momentum all mediate the relationship.
Regional fertility
World fertility, 1950–2100
Current TFR ≈ 2.2
Global aggregate.
Why One Fertility Number Does Not Determine the Future
A common reading equates a below-replacement fertility rate with automatic population decline. The relationship is more complex. Population change depends on the interaction of several forces:
- Cohort size. A large generation of women of childbearing age can produce many births even at a low fertility rate, so population can keep growing for decades after fertility falls below replacement.
- Timing of births. When women have children later, period fertility falls even if completed fertility does not.
- Mortality. Falling mortality, especially at young ages, offsets some of the effect of lower fertility.
- Migration. Net migration can sustain or reverse population change independently of fertility.
- Demographic momentum. A young age structure built by past high fertility continues to drive growth long after fertility declines.
- Age structure. Whether a population grows or shrinks depends on the balance between births, deaths and the size of each age cohort, not on fertility alone.
This is why NATION CONTINUITY presents fertility alongside generations, natural change and migration rather than as a single predictive indicator.