Peer-reviewed article
Demographic Change and Life Expectancy in Nigeria: Assessing the Effects of Fertility, Infant Mortality, Population Growth and Net Migration
Ugochukwu Pascal Agba ·
Summary
Written by AI, not yet AICS's view · claude-sonnet-5-5This study uses national yearly data from 1991 to 2025 to examine how fertility rate, infant mortality, population growth and net migration relate to life expectancy in Nigeria. It finds a stable long-run relationship among these variables. Higher infant mortality and faster population growth were linked to lower life expectancy. Fertility showed an unexpected positive link, which the authors interpret cautiously. The authors recommend reducing infant mortality and strengthening maternal and child health services.
Key points
- A stable long-run relationship was found among the variables.
- Infant mortality rate had a significant negative effect on life expectancy.
- Population growth rate had a significant negative effect on life expectancy.
- Fertility rate had a positive and statistically significant effect, which the authors say may reflect improved maternal and child healthcare and wider socioeconomic progress rather than a direct benefit.
- Net migration had a negative but statistically insignificant relationship with life expectancy.
Limitations
The study uses national aggregate time-series data and cannot show causal effects, and the authors note that endogeneity should be addressed in future work using panel datasets. It also cannot explain the unexpected positive fertility result, and it does not look at children directly beyond the infant mortality indicator.
Abstract
This study investigates the effects of fertility rate, infant mortality rate, population growth rate, and net migration on life expectancy in Nigeria over the period 1991-2025. The study was motivated by limited empirical evidence on the combined influence of key demographic variables on longevity despite their importance for health and development policy. Annual time-series data were analysed using the Autoregressive Distributed Lag (ARDL) approach following Phillips Perron unit root tests and ARDL bounds cointegration analysis. The results confirmed the existence of a stable long-run relationship among the variables. Fertility rate exerted a positive and statistically significant effect on life expectancy, whereas infant mortality rate and population growth rate exhibited significant negative effects. Net migration showed a negative but statistically insignificant relationship with life expectancy. Diagnostic tests revealed no evidence of serial correlation or heteroskedasticity, while normality, specification, and stability tests confirmed the robustness and reliability of the estimated model. The findings suggest that demographic characteristics remain important determinants of life expectancy in Nigeria. The unexpected positive fertility coefficient is interpreted cautiously because it may reflect improvements in maternal and child healthcare, broader socioeconomic progress, and unobserved structural factors rather than a direct beneficial effect of higher fertility. The study concludes that sustained reductions in infant mortality and effective population management are essential for improving longevity. It recommends strengthening maternal and child healthcare services, expanding primary healthcare coverage, promoting voluntary family planning and reproductive health education, and improving demographic data systems. Future research should employ panel datasets to address endogeneity in Nigeria.