Where do the heaviest children come from? A prospective study of white children from birth to 5 years of age.

A prospective follow-up study, from birth to age 5, of height, weight, and weight/height indices in 582 white children was carried out in a suburban private pediatric practice. The purpose of the study was to examine trends in height and weight over time, to evaluate any differences in measures of ponderosity between breast-fed and bottle-fed infants, and to locate the heaviest children at age 5. There were significant correlations between height, weight, the ratio of height to weight, the ponderal index (height/weight 1/3), and the Quetelet index (weight/height2) achieved during the first year of life, and that attained at age 5 years. However, approximately 70% of the variance in weight and ponderosity indices at age 5 could not be accounted for by measurement of weight and ponderosity during the first year of life. Breast-fed and bottle-fed infants did not differ in weight and weight/height indices. There was a modest, but consistent, "tracking" pattern among children in the upper decile for weight and ponderosity at age 5 years in that 30% of them were also in the top decile for weight and ponderosity at age 6 months, and 30% to 40% were in the top decile at age 1 year. More than half of the variance in weight or indices of body proportion at age 5 is not accounted for by these variables in the first year of life, indicating limitations to the generalizability of the concept, that obese infants become obese children.