Euro-Growth references for body mass index and weight for length. Euro-Growth Study Group.

BACKGROUND

Fully longitudinal data from the multicenter Euro-Growth study (21 study sites; n = 2145 children) were used to develop sex-specific percentiles and Z-scores for body mass index (BMI) and weight for length (WfL) during the first 36 months of life.

METHODS

Smoothed percentile curves for BMI against age were constructed and checked against raw percentiles. Smoothed percentile curves for WfL were constructed according to established procedures and were checked against raw percentiles. The relation of BMI with length and of WfL with age was examined. The relation between BMI and WfL was tested using z-scores of each. The influence of gender, geographic location (study site), and genetic factors 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 gradual decline between 12 and 36 months. Smoothed percentiles for WfL showed only small deviations from raw percentiles. BMI was found to be essentially independent of length, whereas WfL showed some degree of dependence on age. Values for BMI and WfL showed very good agreement, except at the extremes of 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 WfL provide improved tools for health workers and researchers dealing with childhood obesity.