Maternal socioeconomic position and inequity in child deaths: An analysis of 2012 South Korean birth cohort of 466,636 children

•From the analysis of the South Korean Birth Cohort, different patterns of social inequalities in child mortality were identified by the child's age.•We confirmed that congenital cause (neonatal period), unknown cause (post-neonatal period), and injury and external cause (childhood) were the main causes of inequalities in mortality.•We also identified that the greatest inequalities occurred in the post-neonatal period.•Strengthening the health system and multisectoral efforts that consider families' and children's needs under the spatial context may be necessary.