Decomposing the gap in under-five mortality determinants between the low- and high-risk regions of Nigeria.

Nigeria has the highest burden of under-five mortality (U5M) in the world and contributes 17% of the global childhood deaths. The high national average of U5M in Nigeria is driven by the rates in some regions of the country. This study quantifies the contributions of socioeconomic, bio-demographic, and health-related factors in explaining the gaps in U5M between the country's low-risk regions (LRR) and high-risk regions (HRR). The study performed spatial analysis (using Local Moran's I spatial analysis) and Blinder-Oaxaca decomposition analysis of the gap in U5M determinants between the LRR and HRR on a sample of children born five years before the 2018 Nigeria Demographic and Health Survey (n = 32,234). Spatial analysis shows that the North-west and parts of the North-east regions were hotspots for U5M, while the South-west and parts of the South-east were coldspots. Results from the decomposition analysis revealed a prevalence of 6.1% in LRR compared with 11.3% in HRR. This translates to 58.9% higher U5M in HRR relative to LRR. The study concludes that interventions aimed at enhancing factors like maternal education, access to economic resources, family planning uptake, and increasing birth intervals in HRR could be effective in reducing high U5M in Nigeria.