RESUMEN
Births in avoidable high-risk contexts defined by the interplay of sub-optimal childbearing age, short spacing, and first and high birth order incur elevated risks of childhood death. However, the extent of disparities in risks of dying in infancy vis-à-vis the continuum of non-high-risk and (un)avoidable high-risk attributes at birth as determined by mother's age at childbirth, child spacing, and birth order characteristics is yet to be adequately explored in Nigeria as elsewhere. To fill this gap, chi-square association test and Cox's proportional hazards regression were used to analyze data of 31,260 nationally representative children aged 0-59 months drawn from 2013 Nigeria Demographic and Health Survey. Disparities in infant mortality risks were mainly examined across the spectrum of birth-related risk attributes at birth broadly categorized as no extra high-risk, unavoidable first- order risk and combined avoidable high-risk. The risks of dying in infancy differed significantly by risk attributes to the extent dictated by other confounders. Also, infant mortality risks varied significantly by all moderating factors excluding religion, water source, toilet type and place of delivery. Interventions targeted at reducing avoidable high-risk fertility rate and strengthening health system to provide life-saving care to most-at-risk children would engender rapid improvement in infant survival.