To compare the distribution of body mass index (BMI) in a national representative study in The Netherlands in 1996-7 with that from a study in 1980. Cross sectional data on height, weight, and demographics of 14 500 boys and girls of Dutch origin, aged 0-21 years, were collected from 1996 to 1997. BMI references were derived using the LMS method. The 90th, 50th, and 10th BMI centiles of the 1980 study were used as baseline. Association of demographic variables with BMI-SDS was assessed by ANOVA. BMI age reference charts were constructed. From 3 years of age onwards 14-22% of the children exceeded the 90th centile of 1980, 52-60% the 50th centile, and 92-95% the 10th centile. BMI was related to region, educational level of parents (negatively) and family size (negatively). The -0.9, +1.1, and +2.3 SD lines in 1996-7 corresponded to the adult cut off points of 20, 25, and 30 kg/m(2) recommended by the World Health Organisation/European childhood obesity group. BMI age references have increased in the past 17 years. Therefore, strategies to prevent obesity in childhood should be a priority in child public health.
