Breast-feeding and growth in Brazilian infants.

A new international growth reference is being prepared based on children who are fed according to World Health Organization recommendations, which entail exclusive breast-feeding for the first 4-6 mo of life. However, the number of exclusively breast-fed infants in most societies is small, so that selection biases may result from using such a population. We examined the variability in linear and soft tissue growth of infants according to their feeding patterns, emphasizing differences between exclusively and predominantly (breast milk plus fluids) breast-fed infants. About 650 infants from a relatively developed urban area in southern Brazil were examined at the ages of 1, 3, 6, and 12 mo, and an additional 800 infants at 6 and 12 mo. At each visit, infants were weighed and measured and a 24-h dietary recall was completed with the infants' caretakers. In the analyses of growth, care was taken to address the biases of reverse causality, regression to the mean, and confounding. There was little association between feeding pattern and growth in the first month. From 1 to 3 mo, partially breast-fed infants tended to gain more weight, followed by those who were completely weaned. From 3 to 6 mo, fully weaned infants grew fastest in weight and length and exclusively breast-fed infants grew slowest. After 6 mo of age, the growth in length of partially breast-fed and fully weaned infants was similar, but the latter gained more weight. There were virtually no differences between exclusively and predominantly breast-fed infants in the first 6 mo of life. There results suggest that both of these groups may be pooled for the purpose of constructing growth references.