Is prolonged breast-feeding associated with malnutrition?

The association between duration of breast-feeding and nutritional status was studied in a population-based sample of 802 children aged 12 to 35.9 months in Southern Brazil during 1982. The prevalence of malnutrition (low weight for age, length for age, and weight for length) was smallest in those children breast-fed for 3 to 6 months, but after this age nutritional status appeared to be worse in those breast-fed for longer. Children still being breast-fed at the time of the survey presented with a significantly higher prevalence of low weight for length than those who had been totally weaned, and those receiving breast-plus bottle-feeding presented with intermediate levels. This association could not be explained by a number of possible confounding variables using a multiple logistic regression analysis. These results are also consistent with a controlled trial on supplementary feeding in the Sudan.