Growth of exclusively breast-fed infants from a poor urban population.

The growth of two groups of infants were evaluated, one of them exclusively breast-fed (105 infants) and the other exclusively bottle-fed (61 infants), and compared with one another and with international standards (NCHS). All infants were evaluated by anthropometry at 1, 2, 3, 4, 5 and 6 months of age. A fourth order polynomial was adopted for each infant and for each anthropometric measurement in order to estimate individual growth, and the 5th, 50th and 95th percentiles for weight and length were obtained. For the age of 6 months, the weights of breast-fed boys and girls were always statistically equal to or higher than those of infants fed cow's milk or those of NCHS standards. Breast-fed boys presented significantly longer length than bottle-fed boys but shorter than NCHS standards, and breast-fed girls presented significantly shorter length than both bottle-fed girls and than NCHS standards. The greater weight of exclusively breast-fed infants when compared to NCHS standards at six months of age, which differentiates the present study from several other ones carried out in developing countries, was probably due to the association of the beneficial effects of breast-feeding with those of pediatric follow-up.