Associations between breastfeeding and cognitive function in children from early childhood to school age: a prospective birth cohort study

Background Despite evidences of breastfeeding for preventing acute physical illnesses in infants, the evidence for the association between breastfeeding and long-term cognitive development is not yet convincing. Methods The data of nationwide representative sample of 1752 children born between 2008 and 2009 in Korea were prospectively assessed from the fetal period to examine the benefits of breastfeeding and cognitive development. Breastfeeding duration was prospectively assessed by parents. The Korean Ages and Stages Questionnaire and the Korean version of Denver II were used to assess early development annually from 5.5 to 26.2 months of age. Language development at 3 years of age was assessed with Receptive and Expressive Vocabulary Tests. Cognitive function at 8 years of age was assessed using multifactorial intelligence test. Results In the analysis of categorical variables, children who were breastfed for > 1 and <= 3 months displayed significantly higher odds ratios for delayed development assessed with Korean Ages and Stages Questionnaire at 14.1 months than those breastfed for > 3 and <= 6 months (OR = 2.21; 95% CI: 1.08, 4.50), but no significant differences in other rounds of assessments. In the analysis with continuous variables, there were significant differences among six groups of breastfeeding duration in communication (F = 3.72;p < 0.002) and problem solving (F = 3.09;p < 0.009) at 14.1 months, expressive language (F = 3.74;p = 0.002) at 3 years, and calculation (F = 2.43;p < 0.033) at 8 years. When analyzed by two groups, children breastfed for > 3 months scored significantly higher on the communication (F = 17.71;p < 0.001) and problem-solving (F = 11.26;p < 0.001) subscales at 14.1 months, and expressive language (F = 12.85;p < 0.001) at 3 years, and vocabulary (F = 6.78;p = 0.009) and language inference (F = 5.62;p = 0.018) at 8 years, compared to children breastfed for 3 months or less. Conclusion We found that cognitive development was improved in children that were breastfed for > 3 months. Although these results are supported by previous studies, it is important to note that other factors were reported as larger determinants of cognitive development than breastfeeding. Future studies that examine the underlying mechanism for the association between breastfeeding and cognitive development are warranted.