Demographic transition: fertility, the key to West Africa's dividend

A single figure sums up the entire debate over West Africa's economic future: 6.06 children per woman in Niger, against 3.4 in Ghana. The highest fertility in the world and a fertility on the path to convergence coexist just a few hundred kilometres apart, in one and the same region, under similar climates and cultures. This gap of one to 1.8 is not a statistical curiosity. It determines the age structure of each country, the number of mouths to feed per worker, the savings available per head and, ultimately, the capacity of each nation to turn its youth into an engine of growth rather than a burden. The demographic dividend, that surplus of growth which lifted East Asia, does not fall from the sky: it opens, or closes, depending on whether fertility falls or stalls. The West African question is therefore not whether the region is young, it is, but whether it decides to open this window before it closes again.

Two demographic worlds in one region

The World Bank's 2023 data reveal a striking dispersion of fertility across West Africa. At the top, Niger peaks at 6.06 children per woman, the highest rate on the planet, followed by Mali (5.61). At the other end, Ghana falls to 3.4 and Senegal to 3.82, two countries that have entered an advanced transition. Benin sits at 4.56, in an intermediate group with Nigeria (4.48), Côte d'Ivoire (4.28), Togo and Burkina Faso (4.19 each). This ranking does not map onto any chart of religions or traditions: countries with comparable cultural profiles appear at both ends. The fertility hierarchy therefore tells less a story of immutable culture than a story of public policy, access to contraception and girls' schooling. That is good news, because policies, unlike supposedly fixed cultures, are decided and financed.

Ghana tipped over, Niger stalled: the demonstration by the curves

Comparing two trajectories over three decades is the best antidote to fatalism. Between 1990 and 2023, Ghana drove its fertility down from 5.74 to 3.4 children per woman, a steady, continuous decline that brought it close to the generational replacement threshold. Over the same period, Niger moved from 7.81 to 6.06: a real but late inflection, which only truly begins after 2010 and leaves the country barely below its historical peak. In 1990 the two countries were certainly far apart, but on comparable slopes; thirty years later, the gap has widened into a chasm of age structure. The signal is clear: what distinguishes the two trajectories is not nature, but the intensity and consistency of investment in family planning and girls' education.

Benin illustrates the middle path and its ambiguity. At 4.56 children per woman in 2023 according to the World Bank, the transition is under way but slow: each woman still bears more than four children, and the age structure remains very young, with 43% of the population under 15 in 2024. This is the precondition of a future dividend, but a condition that is not enough on its own: a young population is an asset only if it subsequently tips towards a majority of working-age people. As long as fertility stays above four, that tipping point keeps being deferred, and the country continues to run behind its own needs for schools, health centres and, tomorrow, jobs.

Ghana drove its fertility down from 5.7 to 3.4 children per woman while Niger stayed at 6.1. The same region, a generation apart: proof that fertility is not a fate, but a public-policy choice.

Understanding the dividend: a window, not a gift

The demographic dividend is neither magical nor automatic. It appears when falling fertility reduces the share of dependent children and swells, for a few decades, the working-age population relative to dependants. This favourable imbalance frees up savings, lightens spending per child and can, if it is accompanied, translate into accelerated growth. But international experience is categorical: the window pays off only if three levers are pulled at once, voluntary family planning that triggers the fertility decline, girls' education that consolidates it and youth employment that absorbs the growing active cohort. Without these three conditions, a young population becomes a burden rather than an engine, a mass of dependants that too few workers must carry.

The dependency ratio measures precisely this weight. In Niger, nearly 98 dependants, children and elderly combined, weigh on 100 working-age people; in Ghana, they number only 66. Put another way, each Ghanaian worker carries a third less burden than a Nigerien counterpart. It is this differential that stifles or frees up savings and investment per head: at equal income, the high-dependency country devotes the bulk of its resources to the daily survival of a mass of children, while the low-dependency country can save, invest and equip itself with the infrastructure of its future growth.

The central bottleneck: unmet demand for contraception

If fertility remains high, it is not primarily because all women would wish for large families, but because many cannot space or limit their births for lack of means. Contraceptive prevalence, all methods combined, ranges from 36.3% of women aged 15 to 49 in Ghana to only 15.3% in Niger, the lowest of the nine reference countries. Benin sits at 22.4%, mid-table, but this figure calls for a crucial caveat: it aggregates all methods, including traditional ones; prevalence of modern methods alone, the most reliable, is markedly lower there, on the order of 12% according to national surveys. Conflating the two measures would vastly overstate the actual coverage of needs.

The scale of the unmet need can be quantified at the regional level. In the nine French-speaking countries of the Ouagadougou Partnership, 8 million women had an unmet need for modern contraception in 2018: they did not want a child within two years but were using no modern method. This is not a question of fertility desire, it is a question of supply, product availability, proximity of services and information. Meeting this latent demand is the most direct, most consensual and least costly lever for accelerating the transition, because it merely gives women the means to fulfil their own intentions.

What the region has already proven: Ouagadougou's contraceptive revolution

The challenge may seem out of reach; yet it has already begun to be met within the region itself. From 2011 to 2021, the nine countries of the Ouagadougou Partnership added roughly 4 million modern-contraception users. According to estimates, this progress made it possible to avert nearly 18.8 million unintended pregnancies and about 63,700 maternal deaths over the decade. These figures demonstrate two things. First, that demand exists and responds to supply as soon as it becomes available. Second, that the stakes are not only demographic: every unintended pregnancy averted is a woman's life preserved, a schooling that continues, a family budget that can breathe. The fertility transition and maternal health advance hand in hand.

The order of magnitude of the financial effort is known and documented. In the Sahel, the regional SWEDD project, endowed with 200 million dollars and backed by the World Bank, illustrates the kind of structured investment (empowerment of women and girls, reproductive-health provision) that the region is already mobilising. The social return on this spending, measured in maternal deaths averted and unintended pregnancies prevented, places voluntary family planning among the public investments with the highest returns, provided it is targeted and monitored over time.

The forgotten lever: adolescent fertility

A decisive share of the fertility reserve is at play in adolescence, and it is perhaps the most cost-effective lever of all. Fertility among girls aged 15 to 19 ranges from 58 births per 1,000 in Ghana to more than 145 in Niger, a ratio of 1 to 2.5. Benin sits at 77.8, a high level that weighs heavily on the future. For early motherhood sets off a vicious circle: it shuts the door of school, deprives the young girl of the years of education that would have reduced her total fertility, and thus mechanically perpetuates the high fertility of the next generation. A birth at sixteen most often means an interrupted schooling, a truncated human capital and a high-fertility trajectory locked in for twenty years.

The lever is therefore twofold and self-reinforcing: keeping girls in school pushes back the age of first motherhood, reduces total fertility and prepares the skilled workforce the dividend needs in order to materialise. Girls' education is not one social policy among others, it is the pivot around which the fall in fertility and the formation of human capital are articulated. It is also one of the areas where data disaggregated by age, sex and setting are most cruelly lacking to target action.

The cost of inaction: every year counts

Persistently high fertility is not neutral: it dilutes every public franc invested among an ever-growing number of children. Less school per pupil, less health per patient, less savings per household: social spending is permanently chasing a demographic base that keeps expanding. Niger offers the extreme illustration with population growth of 3.3% a year, among the fastest in the world. At that rate, the population doubles in one generation, about 21 years. Doubling a population in one generation means having to double the number of classrooms, health centres and jobs simply to maintain the level of service per inhabitant, before even thinking of improving it. The cost of inaction is therefore not deferred, it is paid every year, in overcrowded schools, rationed health care and a dividend pushed back by just as much.

The stakes are also read in the geography of the masses. Nigeria, with 227.9 million inhabitants in 2023, accounts on its own for 56% of the combined population of the nine reference countries, which total 406 million. This concentration has a direct consequence for any regional analysis: an inflection in Nigerian fertility, or the absence of one, on its own determines the demographic trajectory of West Africa as a whole. No regional dividend strategy holds if it does not place Nigeria at the centre of its calculation.

What regional averages hide

One point is decisive for action: regional figures are averages, and averages mask what matters most. A national fertility of 4.56 in Benin covers opposing realities between a schooled capital where the transition is already advanced and rural areas of the north where it is barely begun. Behind a national dependency ratio lie considerable gaps between urban and rural settings, between levels of wealth and education. The aggregate indicator, useful for comparing countries, does not say where to act within a country. Yet that is precisely where the effectiveness of a policy is decided: the same family-planning budget does not produce the same effect depending on whether it targets areas of high unmet demand or areas already well covered. Without fine-grained measurement, by region and by setting, public investment advances blind.

This is the conviction that guides CRAD's work on population and public-health questions. The debate over the demographic dividend is played out first on the quality of measurement: fertility, contraceptive prevalence, age structure, girls' schooling, unmet need, all disaggregated by region, by setting and by living standard. CRAD designs the field surveys and dashboards that turn these indicators into concrete decisions for states and funders. Mapping unmet demand area by area means turning a national statistic into an investment roadmap, and moving population policy from intention to precision.

This grounding is not theoretical. CRAD built its expertise on major population surveys (DHS, MICS) and on field measurement disaggregated by sex, notably through the regional WOCEWA project which documented gender equality in twelve ECOWAS countries. The same methodological rigour applies to the demographic transition: without geolocated, repeated and disaggregated data, family-planning and girls'-education policies risk scattering their resources far from the areas where the dividend is actually won.

The Asian precedent: what the dividend paid elsewhere

The stakes may seem abstract; their effects, however, are quantified. The seminal work of Bloom and Williamson estimates that the demographic dividend contributed up to a third of the acceleration in East Asia's GDP per capita growth between 1965 and 1990, that is between 1.4 and 1.9 additional percentage points of annual growth. This shift was no accident: it followed a rapid and deliberate fall in fertility, accompanied by massive investment in education and employment. For Africa, the same analysts project a potential gain of 0.5 to 2 points of GDP per capita per year over five decades, provided there is investment in employment, health and girls' education. The order of magnitude is considerable: over a generation, it makes the difference between a region that takes off and a region that plateaus.

The precondition and the condition: youth is not dividend

One confusion must be cleared up, for it underpins much misplaced optimism: the youth of a population is the precondition of the dividend, it is never its guarantee. In Benin, 43% of the population is under 15 in 2024. This very young structure is often presented as an asset in itself. It is one only on a single condition: that fertility falls fast enough for this cohort of children to become tomorrow a majority of workers, and that the economy be ready to offer them jobs. If fertility stays high, the population merely grows younger without ever tipping over, and the window does not open. Youth is a fuel; without the engine of falling fertility and without the transmission of education and employment, it produces no movement.

• Voluntary family planning triggers the fall in fertility by meeting the needs of the 8 million women of the Ouagadougou Partnership whose need for modern contraception remains unmet.
• Girls' education consolidates this decline and pushes back early motherhood, today responsible for 78 to 145 births per 1,000 adolescents depending on the country.
• Youth employment turns the growing active cohort into growth; without it, the fall in dependency produces neither savings nor productivity.

These three levers work only together and over time. Pulling the contraception lever without schooling girls, or freeing up a workforce without creating jobs, amounts to opening the window onto a wall. The Ghanaian experience and Ouagadougou's contraceptive revolution show that the region knows how to pull these levers; the challenge now is to hold all of them, everywhere, over a decade, and to measure their effects where they play out, that is at the subnational level.

At bottom, the West African demographic transition is not an unsolved scientific problem: we know how to bring fertility down, and immediate neighbours have done it. It is a problem of political consistency and of steering by data. The countries that advance are those that set a target, finance family planning and girls' education, sustain the effort over a decade and measure their results by region. Those that stall do not lack youth: they lack a compass. Opening the dividend window means first deciding to measure fertility and its determinants, then never letting go of them.

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