Role of Parental Social Class in Preterm Births and Low Birth Weight in Association with Child Mortality: A National Retrospective Cohort Study in Korea

Abstract

Purpose: We explored the role of parental social class in preterm birth (PTB) and low birth weight (LBW) in association with child mortality in Korea. Materials and Methods: A total of 7,302,732 births in Korea between 1995 and 2007 were used for designing the national retrospective cohort study. Kaplan-Meier survival curves and Cox proportional hazard models were used to determine the risk of child death after adjusting for covariates. Results: Parental social class was associated with adverse birth outcomes and child mortality in Korea. Parental social class increased the strength of the relationship of adverse birth outcomes with child mortality. Child mortality was higher among PTB and LBW infants from parents with a lower social class than normal births from parents with a higher social class. In particular, the disparity in child mortality according to parental social class was greater for LBW and PTB than intrauterine growth retardation births. When one of the parents had a middle-school education or lower, the disparity in child mortality due to adverse birth outcomes was large regardless of the other spouse's educational status. Inactive economic status for the father, as well as an occupation in manual labor by the mother, increased the risk of child mortality. Conclusion: Strong relationships for social inequalities and adverse birth outcomes with inequalities in child mortality in South Korea were found in this study. Tackling social inequalities, as well as reducing adverse birth outcomes, are needed to reduce the disparities in child mortality in South Korea.