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

Background: Inequalities in child mortality occur via interactions between socio-environmental factors and their constituents. Through childhood developmental stages, we can observe changing patterns of mortality. By investigating these patterns and social inequalities by cause and developmental stage, we aim to gain insights into health policies to reduce and equalize childhood mortality. Methods: Using vital statistics, we examined the Korean birth cohort of 2012, including all children born in 2012 up to five years of age (N = 466,636). The dependent variables were all-cause and cause-specific mortality by developmental stage (i.e., neonatal, post-neonatal, and childhood). A Cox proportional hazard regression model was built to compare child mortality according to maternal education. The distribution of inequalities in cause-specific mortality by child age was calculated using the slope index of inequality (SII). Results: Inequalities in child mortality due to maternal education occur during the neonatal period and increase over time. After adjusting for covariates, the Cox proportional hazard models showed that “injury and external causes” (HR = 2.178; 95% CI = [1.283–3.697]) and “unknown causes” (HR = 2.299; 95% CI = [1.572–3.363]) in the post-neonatal period, and “injury and external causes” (HR = 2.153; 95% CI = [1.347–3.440]) in the childhood period significantly contributed to socioeconomic inequalities in child mortality. For each period, the leading causes of inequality were identified as follows: “congenital” (96.7%) for the neonatal period, “unknown causes” (58.2%) and “injury and external causes” (28.4%) for the post-neonatal period, and “injury and external causes” (56.5%) for the childhood period. Conclusion: We confirmed that the main causes of death in mortality inequality vary according to child age, in accordance with the distinctive context of child development. Strengthening the health system and multisectoral efforts that consider families' and children's needs according to spatial contexts (e.g., home, community) may be necessary to address the social inequalities in child health.