Excessive weight gain in exclusively breast-fed infants

BACKGROUND: Breastfeeding is recommended as the best source of nutrition in the first months of life and observational studies have associated exclusive breastfeeding with decreased weight gain and a protective effect against obesity in childhood. The objective of this study was to describe the characteristics of a cohort of exclusively breastfed obese infants to determine factors that may lead to this unusual weight gain. METHODS: Infants seen between 2003 and 2015 who were exclusively breastfed and showed excessive weight gain in the first year of life were followed with a focus on features of the mother, the child, feeding patterns and the presence of concomitant factors that influence nutritional status. Additionally, in a subset of the sample, macronutrients of the maternal breast milk were analyzed. A descriptive, prospective cross-sectional study was conducted. RESULTS: Of 73 patients, 63% were girls. At 3 months of life, 64% had a weight-for-height standard deviation score (SDS) >2. At 6 and at 12 months, 100% of the patients had a weight-for-height >2 SDS. The mean age at semisolid-food introduction was 7 months. The mean age at weaning was 15.8 months. The babies were fed on demand and no hunger-satiety pattern was observed. In the breast milk samples analyzed, a significantly lower fat content was found. CONCLUSIONS: The results of our study lead to the assumption that inter-individual variations in mother's milk composition may affect the growth patterns of children.