Abstract. Impact of breastfeeding on the intelligence quotient of eight-year-old children1

ObjectiveThis study aimed to determine the influence of breastfeeding on the intellectual capacity of children from a cohort in a developing country, with a control for the main confounding factors.MethodsA prospective cohort study was performed including all infants born in the hospitals of a medium-size city, and a random sample of these newborns was monitored at 30, 90, and 180 days of life, and at age 8 years. Several aspects of breastfeeding were assessed in the follow-up and, at 8 years, general intellectual capacity was assessed through the Raven's Colored Progressive Matrices test. The statistical analyses used Student's t-test, -ANOVA, and linear regression and logistics, considering p-values less than 0.05 as statistically significant associations.ResultsAt age 8 years, 560 children were assessed with Raven's Colored Progressive Matrices test. The average score was 22.56 points, with a standard deviation of 5.93. The difference in the averages found between the breastfed and non-breastfed groups at six months of age was 1.33 (p = 0.008). Mother's and child's skin color, social and economic class, maternal education and smoking, and breastfeeding at six months of age (p = 0.007) were still associated with the outcome.ConclusionsChildren that were breastfed for six months or more had better performance in the general -intellectual assessment, even after adjusting for the main confounding factors