Euro-Growth references for body mass index and weight for length

Background: Fully longitudinal data from the multicenter Euro-Growth study (21 study sites; n = 2145 children) were used to develop sex-specific perce ntiles and z-scores for body mass index (BMI) and weight for length (WfL) d uring the first 36 months of life. Methods: Smoothed percentile curves for BMI against age were constructed an d checked against raw percentiles. Smoothed percentile curves for Wa were c onstructed according to established procedures and were checked against raw percentiles. The relation of BMI with length and of WfL with age was exami ned. The relation between BMI and WfL was tested using z-scores of each. Th e influence of gender, geographic Location (study site), and genetic factor s on BMI and WfL was examined. Finally, the new references for BMI and WfL were compared with other published references. Results: Selected percentiles (P; P3, P5, P10, P25, P50, P75, P90, P95, and P97) for BMI showed a sharp increase from 1 to 6 months of age and a gradu al decline between 12 and 36 months. Smoothed percentiles for WfL showed on ly small deviations From raw percentiles. BMI was found to be essentially i ndependent of length, whereas WfL showed some degree of dependence on age. Values for BMI and WfL showed very good agreement, Except at the extremes o f the age range. A modest degree of influence of geographic location on BMI and WfL was found. Correlations with parental BMI and WfL, were very weak, however. Comparison with the National Center for Health Statistics (NCHS) references showed the latter to have a narrower range of values. Conclusions: The new Euro-Growth references for BMI and Wa provide improved tools for health workers and researchers dealing with childhood obesity. ( C) 2000 Lippincott Williams & Wilkins, Inc.