Aim: To examine whether duration of breast feeding has any effect on a child's cognitive or motor development in a population with favourable environmental conditions and a high prevalence of breast feeding.
Methods: In 345 Scandinavian children, data on breast feeding were prospectively recorded during the first year of life, and neuromotor development was assessed at 1 and 5 years of age. Main outcome measures were Bayley's Scales of Infant Development at age 13 months (Mental Index, MDI; Psychomotor Index, PDI), Wechsler Preschool and Primary Scales of Intelligence (WPPSI-R), and Peabody Developmental Scales at age 5.
Results: Children breast fed for less than 3 months had an increased risk, compared to children breast fed for at least 6 months, of a test score below the median value of MDI at 13 months and of WPPSI-R at 5 years. Maternal age, maternal intelligence (Raven score), maternal education, and smoking in pregnancy were significant confounders, but the increased risk of lower MDI and total IQ scores persisted after adjustment for each of these factors. We found no clear association between duration of breast feeding and motor development at 13 months or 5 years of age.
Conclusion: Our data suggest that a longer duration of breast feeding benefits cognitive development.