The lethal gradient: wealth, education and geographic inequalities in neonatal, infant and under-five mortality in Nigeria, evidence from the 2023–24 Demographic and Health Survey

Background Nigeria contributes a significant proportion of under-five mortality worldwide, but averages may be masking the disparities in the distributions of these risks. This study estimated socio-economic and geographic inequalities in neonatal, infant and under-five mortality, the attributable deaths and their predictors. Methods This study examined 54 971 live births in the 10 years prior to the 2023-24 Nigeria Demographic and Health Survey and estimated mortality rates with the synthetic cohort life-table method, measured inequality using rate ratios, population attributable fractions and the Erreygers concentration index; and decomposed the latter. We used survey-weighted discrete-time survival models to study under-five mortality in 27 554 recent births. Results The under-five mortality rate was 110.1 per 1000 live-births (95% CI 103.4-117.5) in the five years preceding the survey. Over ten years this was 139.7 per 1000 in the poorest wealth quintile and 49.1 in the richest, ratio 2.85, and 129.7 among children born to mothers without any education vs. 43.2 among children born to mothers with higher education. Inequality by wealth ratio increased to 1.43 (neonatal), 3.07 (post-neonatal) and 6.82 (1–4 years or child mortality). If all children experienced mortality rates of the richest quintile, 52.5% of under-five and 77.1% of 1–4-year-old deaths would not have occurred. Most of under-five mortality inequality was attributable to household wealth (45.5%), then to geopolitical zone (33.2%) and rurality (17.5%). Adolescent mothers, short birth interval (less than 24 months) and multiple birth increased risk. Conclusions In Nigeria the impact of socio-economic disadvantage on death is most devastating after the first month of life. Abolishing wealth inequalities in mortality would eliminate 50% of all deaths in children under 5. Eliminating disparities demands child survival efforts in North West, North East and poor rural places, progress in girls' schooling and family planning, and quality newborn care.