C H A P T E R 2 Table 4: height, weight and corresponding BMI values of the 3rd, 50th and 97th percentile of a 10-‐year 36 old boy. Boy, 10 years Height (cm) Ideal Weight (kg) BMI (kg/m2 ) P3 129 24.7 14.84 P50 141 30 15.09 P97 152 37.5 16.32 Although the BMI is the usual ratio to express weight for height related to age, weight plotted against height independent of age is a more reliable comparison in children*. In the Figures 3 and 4 it is seen that there is an increase in weight for height comparing the recent data of Fredriks with the older data of van Wieringen. Although there is a secular trend visible for height, the increasing weight goes be-‐ yond this secular trend, especially for the P97 values resulting in a skewed distribu-‐ tion. This is even more pronounced realizing that in the latest growth study, per-‐ formed in The Netherlands, the secular trend in height has stopped at all. Since 1955 there in an increase in height, but between 1997 and 2010 this increase dis-‐ continued as visible in Table 5. The trend in weight did not stop, according to this study11. Table 5: Final height of boys and girls from 1955-‐2010. 1955 1965 1980 1997 2010 Boys 176.0 cm 178.0 cm 182.0 cm 184.0 cm 183.8 cm Girls 163.0 cm 166.3 cm 168.3 cm 170.6 cm 170.7 cm As is illustrated in the examples of Table 4, the BMI also shows a skewed distribu-‐ tion, in contrast to the original BMI data of Quetelet5. Both data sets are based on prepubertal data. The normal distribution as found by Quetelet has changed in a skewed distribution nowadays. Realizing that the BMI is defined as weight divided by the squared height, the secular trend must be more pronounced for weight than for height. Conclusion During the last decennia there is no secular trend of height and weight visible dur-‐ ing the intrauterine period, in contrast to the postnatal growth curves. However, the phenomenon of increasing BMI can be partly explained by the increase in height*. Evidently the increase in skewness of the weight distribution must be as-‐ cribed to a metabolic disturbance of the population. According to these data, it is of great importance to take the described trends in weight and height in children into account in general practice. The increase in
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