Abstract

Data from the DARLING (Davis Area Research on Lactation, Infant Nutrition and Growth) study were analyzed to determine whether the slower growth velocity of breast-fed infants should be considered ‘growth faltering’ or is a normal outcome even under optimal conditions. Anthropometry was completed monthly for 46 infants who were breast-fed for at least 12 months. Energy intake was calculated from 4-day records of breast-milk and food intake at 3, 6, 9 and 12 months. Morbidity was recorded weekly. Activity level was assessed at 9 months by a 7-day sleep record and three 30-minute observations of spontaneous activity while awake. At 3, 6, 9 and 12 months, gross energy intake averaged 569, 642, 738 and 844 kcal, or 91, 84, 87 and 92 kcal/kg, respectively. There was no relationship between energy intake at any time point and morbidity during the subsequent 3-month period, nor between intake and activity level or time sleeping at 9 months. Similarly, infants with slow growth velocity (below the 5th percentile) during each quarter were just as healthy and active in the subsequent quarter as those with more rapid growth. Preliminary data from a matched group of formula-fed infants show the expected differences: higher energy intake and growth velocity, but no advantage in activity or risk of illness. These results indicate that relatively low energy intakes and growth velocities among breast-fed infants are normal patterns with no apparent deleterious consequences in this population.