Time trend in height, weight, and obesity prevalence in school children from Northern France, 1992-2000

Objective: The aim of this study was to evaluate the changes in height, weight and in the prevalence of overweight and obesity between 1992 and 2000 in children living in two towns of northern France. Methods: Two cross-sectional studies were performed in every preschool (last section) and primary schools of the two towns in 1992 (383 girls and 421 boys enrolled) and 2000 (296 girls and 305 boys). Children were 5 to 12 year old in both studies. Measurements: Body height and weight were measured, and BMI was calculated (weight/height(2)). Prevalence of overweight and obesity was determined according to the gender- and age- specific cut-offs of the new international reference (IOTF). We also used the 90(th) and the 97(th) percentiles of the French reference gender- and age-specific BMI curves to define two grades of overweight. Results: After adjustment for age, boys were on average 1.5 cm taller in 2000 than in 1992 (p < 0.001), and the same trend was observed in girls (+ 0.9 cm, p < 0.075). Height-adjusted or age-adjusted weight and BMI were significantly higher in 2000 than in 1992. In girls, obesity defined by IOTF criteria increased from 1.6 to 4.4% (p < 0.03) and overweight from 14.1 to 18.6% (p < 0.11). In boys, the change in prevalences was significant only when the less stringent criteria (i.e. the 90(th) percentile of French references) was used (13.8% in 1992 vs 20% in 2000, p = 0.03). Conclusion: Over an 8 years period, there was an increase in height and BMI in both boys and girls. These results show that the increase in the prevalence of obesity is accompanied by a global trend of accelerated growth.