Impact of breastfeeding at 4-6 months of age on preschool neurodevelopmental outcomes: a nationwide population-based study

Abstract

Small-scale and regional observational and interventional studies have reported associations between breastfeeding and healthier development as well as higher IQ in children. However, these findings have not been validated in large nationwide cohorts. We used nationwide data from the Korean National Health Screening Program for Infants and Children (NHSPIC). The study analyzed the impact of feeding type, reported during the first NHSPIC exam at 4-6 months of age, on the occurrence of developmental delays in the preschool period using regression analysis. We adjusted for multiple covariates including sex, place of residence, economic status, prematurity or low birth weight, and the result of the neonatal hearing exam. Developmental status was further specified to six domains: gross motor, fine motor, cognition, language, sociality, and self-care skills. Among the 1,769,897 children, exclusive breastfeeding (aOR 0.69; 95% CI, 0.67-0.72) and mixed feeding (aOR 0.83; 95% CI, 0.80-0.86) during the age of 4 to 6 months were associated with a significantly lower risk of developmental delay in the preschool period compared to exclusive formula feeding. These associations were consistent across six developmental domains and remained robust in various subgroup analyses and sensitivity analyses.Conclusion: In this nationwide cohort study, breastfeeding during the age of 4 to 6 months was dose-dependently associated with a reduced risk of developmental delays during the preschool years. What is Known:center dot Breastfeeding has been linked to better neurodevelopment in small-scale or regional studies.center dot Evidence from large nationwide cohorts has been lacking.What is New:center dot In a Korean nationwide cohort of 1.7 million children, breastfeeding at 4-6 months was dose-dependently associated with lower risks of developmental delay.center dot The protective association was consistent across six developmental domains and robust in subgroup/sensitivity analyses.