“The developing world” contains too many different histories to describe one demographic condition. India, Brazil, Iran, and Niger do not occupy the same stage. The category is useful here only to correct an old assumption: lower income no longer reliably means high fertility.
India is the clearest case. Its national fertility has fallen to around replacement, though substantial differences remain among states. Southern states moved below replacement earlier; several northern states remain higher. Because India has a large young population, it can add people for decades after the average family becomes smaller.
Latin America’s decline has been among the fastest. Brazil, Chile, and Colombia are below replacement, and Mexico has joined them by recent national estimates. Urbanization and contraception arrived alongside changing unions. The result is a region aging much sooner than its twentieth-century image implied.
Northern Africa and Western Asia are more varied. Fertility has fallen sharply in Iran, Turkey, and several Gulf states, while remaining higher in parts of the region. War and displacement further complicate national totals. Neither religion nor income produces a single trajectory.
The sub-Saharan exception
Sub-Saharan Africa is now the principal concentration of high fertility. The UN reports that the countries with four or more births per woman are mostly in this region, including Chad and Niger. Mortality has fallen, populations are exceptionally young, and fertility remains high enough for rapid growth.
These countries are also among the least productive and materially poorest in the world. That should make us suspicious of the claim that people in rich countries simply cannot afford children. Poor families have children under conditions far harder than a small apartment or an expensive daycare bill. They do so where children contribute household work and kin provide old-age security. Marriage also comes early, while contraception is less available. First-world costs remain real. The comparison shows that “affordability” includes expectations and family structure, not just income.
Even this exception is changing. Fertility is declining in much of the region, although more slowly than earlier projections assumed and unevenly between cities and rural areas. Girls’ education and later marriage are associated with smaller families, as is voluntary access to contraception. Progress in each is uneven, and coercive population targets would repeat old errors.
The demographic future is therefore neither universal decline nor endless growth. Much of the near-term global increase will come from a relatively small group of youthful countries. At the same time, the number of countries below replacement will expand. Both statements can be true because current fertility acts through age structures built over many decades.
Citations
- United Nations, Department of Economic and Social Affairs, Population Division, World Population Prospects 2024: Summary of Results.
- Government of India, Ministry of Health and Family Welfare, National Family Health Survey (NFHS-5), 2019–21.
- Instituto Nacional de Estadística y Geografía, Encuesta Nacional de la Dinámica Demográfica 2023.