Evaluation of growth parameters in a different cohort from the same primary care network indicated that the distribution of growth parameters in this regional population was not well described by the WHO growth curves or by the Centers of Disease Control growth reference, as has been shown in other populations.15–17 To identify a population against which to compare growth, each case was matched to 10 control subjects in the primary care network database by year of birth(61 year), gender, race, and primary care site. Site group (urban versus all others) was used to match when there were insufficient controls in a site. Some controls were excluded during ana lysis because of insufficient growth measurements at the evaluated ages.