Using information from 144 surveys across 34 countries from 1980 to 2020, Pearl Kyei, Samuel Agyei-Mensah, John Casterline and Ayaga Bawah find that the age difference between spouses decreased by 1.7 years from the early 1980s to the late 2010s. Contributing factors are women’s later age at marriage and increase in women’s education.
In many parts of the world, the age gap between spouses has narrowed over time, which is a subtle but telling indicator of shifting gender norms, educational attainment, and marriage market dynamics. Sub-Saharan Africa, a region rich in cultural diversity and complex marital traditions, with the largest spousal age gaps globally, presents an interesting case. In a recent study (Kyei et al. 2025) we offer a comprehensive look at how spousal age differences at first marriage have evolved across 34 countries in the region over the past four decades. The findings? Change is happening, but it is modest and uneven, and intertwined with broader social transformations.
Why spousal age differences matter
Spousal age gaps are more than just numbers. Age differences in marriage reflect power dynamics, social expectations, and economic realities. In many societies, particularly in sub-Saharan Africa, it has long been customary for men to marry significantly younger women (Casterline et al., 1986; Carmichael, 2011; Feng and Ren, 2021). This pattern is often reinforced by social and economic structures that favour youthful brides (South, 1991; Zeng and Liao, 2021).
Large age gaps can also have consequences. Research has linked larger spousal age differences to reduced female autonomy (Casterline et al., 1986; Carmichael, 2011) and lower contraceptive use (Barbieri, Hertrich and Grieve, 2005; Ibisomi, 2014). Therefore, narrowing these spousal age gaps is not just a demographic curiosity; it is a potential marker of progress toward gender equity and healthier relationships.
Scope and methodology
Our study analysed data from 144 nationally representative surveys, 106 Demographic and Health Surveys (DHS), and 38 Multiple Indicator Cluster Surveys (MICS) conducted between 1980 and 2020 (Kyei et al. 2025). The sample included over 920,000 currently married women in their first union across 34 sub-Saharan African countries.
Using linear regression models and five-year marriage cohorts, the analysis examined how spousal age differences have changed over time and what factors have driven those changes. The drivers examined were women’s age at first marriage, educational attainment, religion, type of residence, and whether the marriage was monogamous or polygamous.
Key findings: a slow but steady shift
A first point is that the spousal age gap is larger on average in West Africa countries (up to 12.9 years) and smaller in Eastern and Southern Africa (as small as 4.5 years). And women with more schooling have a smaller spousal age gap.
The average spousal age difference at first marriage declined from 9.3 years in the early 1980s to 7.3 years in the late 2010s: a reduction of two years over four decades, with a statistically significant shift.
The age at first marriage is rising for both men and women. Women’s average age at first marriage increased from 16.5 to 20.7 years between women marrying in 1980-84 and those marrying in 2014–2019. Men’s age at marriage also rose, but by a smaller amount (from 25.7 to 28.0 years). The fact that the women’s age at marriage rose more than men’s explains the narrowing of the spousal age gap, and suggests that that the process is partly driven by the rising age at first marriage and increasing educational attainment among women. As girls stay in school longer and delay marriage, they are more likely to marry partners closer to their own age, often met through school or work rather than arranged by family.
Despite these positive trends, the overall reduction in spousal age differences remains modest. Why? Because men’s age at marriage is also rising, often in tandem with women’s. Economic pressures, such as the need to accumulate resources for bridewealth, may also delay marriage for men as well. Additionally, cultural preferences for younger wives remain strong in these societies, especially where high fertility is still valued.
Final thoughts
The narrowing of spousal age differences at first marriage in sub-Saharan Africa is progressing slowly, unevenly, but unmistakably. This decline is likely reflective of broader shifts in age at first marriage, education, and marriage markets.
These findings have important implications for policymakers, educators, and advocates working to promote gender equality and reproductive health in sub-Saharan Africa. These include continued investments in female education to delay marriage and narrow age gaps; promoting efforts to shift social expectations around ideal spousal age differences through media, community engagement, and religious leaders to help accelerate change, and supporting women’s autonomy through programmes that enhance women’s decision-making power in relationships.
References
Barbieri M, Hertrich V, and Grieve M (2005) Age difference between spouses and contraceptive practice in sub-Saharan Africa. Population, 60(5), 617-54.
Carmichael S (2011) Marriage and power: Age at first marriage and spousal age gap in lesser developed countries. The History of the Family, 16(4), 416-436.
Casterline JB, Williams L and McDonald P (1986) The age difference between spouses: variations among developing countries. Population studies, 40(3), 353-374.
Feng Y and Ren J (2022) Within marriage age gap across countries. Economics Letters, 210, 110190.
Ibisomi L (2014) Is age difference between partners associated with contraceptive use among married couples in Nigeria? International perspectives on sexual and reproductive health, 40(1), 39-45.
Kyei PS, Agyei-Mensah S, Casterline JB, Bawah AA (2025) Trends in spousal age difference at first marriage in Sub-Saharan Africa. Journal of Biosocial Science, 57(4):532-548. doi:10.1017/S0021932025100333
South SJ (1991) Sociodemographic differentials in mate selection preferences. Journal of Marriage and the Family, 53(4), 928-940.
Zeng L and Liao, TF (2021) Social exchange in mate selection of female migrants in China. Marriage and Family Review, 58(3), 199-224.