Nutrients or nursing? Understanding how breast milk feeding affects child cognition

PURPOSE: To explore the associations between type of milk feeding (the “nutrients”) and mode of breast milk feeding (the “nursing”) with child cognition. METHODS: Healthy children from the GUSTO (Growing Up in Singapore Toward healthy Outcomes) cohort participated in repeated neurodevelopmental assessments between 6 and 54 months. For “nutrients”, we compared children exclusively bottle-fed according to type of milk received: formula only (n = 296) vs some/all breast milk (n = 73). For “nursing”, we included only children who were fully fed breast milk, comparing those fed directly at the breast (n = 59) vs those fed partially/completely by bottle (n = 63). RESULTS: Compared to infants fed formula only, those who were bottle-fed breast milk demonstrated significantly better cognitive performance on both the Bayley Scales of Infant and Toddler Development (Third Edition) at 2 years [adjusted mean difference (95% CI) 1.36 (0.32, 2.40)], and on the Kaufman Brief Intelligence Test (Second Edition) at 4.5 years [7.59 (1.20, 13.99)]. Children bottle-fed breast milk also demonstrated better gross motor skills at 2 years than those fed formula [1.60 (0.09, 3.10)]. Among infants fully fed breast milk, those fed directly at the breast scored higher on several memory tasks compared to children bottle-fed breast milk, including the deferred imitation task at 6 months [0.67 (0.02, 1.32)] and relational binding tasks at 6 [0.41 (0.07, 0.74)], 41 [0.67 (0.04, 1.29)] and 54 [0.12 (0.01, 0.22)] months. CONCLUSIONS: Our findings suggest that nutrients in breast milk may improve general child cognition, while nursing infants directly at the breast may influence memory. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s00394-019-01929-2) contains supplementary material, which is available to authorized users.