Growth curves of anthropometric indices in a general population of French children and comparison with reference data.

BACKGROUND: The description of growth patterns of the different anthropometric measurements mainly used in epidemiological studies is useful to better understand the development of obesity in children and its consequences. OBJECTIVE: Our aim was to establish growth curves of anthropometric indices in a general population of French children born during the 1980s and to compare them with the French reference curves based on children born in the 1950s. DESIGN: As part of the Fleurbaix Laventie Ville Santé Studies I and II (FLVS), 441 girls and 467 boys were examined at least twice between 1993 and 2001. Height, weight and four skinfold thicknesses were measured. Body mass index (BMI), sum of peripheral and truncal skinfolds and truncal-to-peripheral ratio were calculated. Mean growth curves from ages 5 to 17 years were assessed for these indices, calculating means and 95% confidence interval per 1 year age group and by gender. RESULTS: Trajectories with age differed importantly according to the index considered; BMI was the one with the smallest difference between genders and the most linear shape with age. From the age of 5 years and after, the FLVS children were on average taller and had a higher subcutaneous adiposity than children born 30 years earlier. Truncal-to-peripheral ratio was higher in our population; this difference became more marked with puberty in girls. DISCUSSION: This study suggests the existence of a secular trend towards a precocious accelerated growth, and a more truncal adiposity distribution, especially in girls. It is a disquieting trend considering its expected consequences on adult health.

Reliability of bioimpedance analysis compared with other adiposity measurements in children: the FLVS II Study.

OBJECTIVE: To evaluate the reproducibility of the measurement of% body fat by bipedal biometrical impedance analysis (BIA) compared with anthropometric measurements of adiposity in children and the correlations between these methods in children and adults. METHODS: A cross-sectional study in a total of 1080 adults and children enrolled in 1999 in the Fleurbaix-Laventie Ville Santé II (FLVS II) population-based study in northern France. The reproducibility of anthropometrical and BIA methods was determined by a nested analysis of variance of repeated measurements by 2 investigators and a bipedal BIA device (Tanita TBF 310) in 64 pupils of two 5th grade classes. The correlation of BIA and anthropometric adiposity measurements with the unknown relative fat mass or volume of the body estimated by a latent adiposity variable (LAV) was established by the triads' method in 1080 subjects of the FLVS II cohort. RESULTS: The reproducibility was similar for the sum of skinfolds, waist circumference and BIA% fat measurements (intraclass correlation coefficients: 0.979-0.992). Correlation coefficient between BIA body fat% and the LAV was higher than 0.86 in all sex and Tanner stage related groups, and similar in children and adults, except in pubertal boys (0.76). CONCLUSION: With a high level of reproducibility, foot-to-foot BIA analysis provides a valuable measurement of total% fat for epidemiologic studies in children. However further studies are needed before extrapolating these results to overweight children.

Changes in physical activity explain paradoxical relationship between baseline physical activity and adiposity changes in adolescent girls: the FLVS II study.

OBJECTIVE: To investigate in adolescents relationships between habitual physical activity (PA) and changes in several indicators of adiposity. DESIGN: Longitudinal population-based study. The Fleurbaix-Laventie Ville Sante II (FLVS II) study in Northern France. SUBJECTS: A total of 222 boys and 214 girls aged 8-18 y, not obese at inclusion. MEASUREMENTS: PA (Modifiable Activity Questionnaire) and adiposity (body mass index (kg/m2), percent body fat by bioimpedance analysis, sum of four skinfolds, waist circumference) were assessed in 1999 and 2001. Adiposity indicators adjusted for age and pubertal stage were compared between groups of baseline PA and between groups of PA changes, separately by sex. RESULTS: At baseline, PA was not associated with adiposity indicators in both sexes. In girls only, being in the group with the highest age-relative level of moderate PA at baseline predicted the highest adiposity gain from baseline to follow-up, for all indicators. After adjustment for baseline values, all adiposity indicators were higher at follow-up in girls who had decreased their relative level of moderate PA during follow-up. In boys, changes in adiposity during follow-up were not significantly different across groups of PA changes. However, the sum of skinfolds at follow-up, adjusted for baseline value, tended to be higher in those who decreased their vigorous PA level and lower in those who increased it. CONCLUSION: In adolescent girls, a decrease in PA rather than inactivity per se may result in increased adiposity over time.

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 pre-school (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.