Social class differences in overweight of prepubertal children in northwest Germany

Objectives: To assess social class differences in overweight and health-related behaviours in 5-7-y-old German children. Design: Cross-sectional study. Setting: Twenty-nine primary schools in Kiel (inhabitants: 248 000), northwest Germany. Subjects: A total of 1350 German 5-7-y-old children and their parents. Main outcome measures: Body mass index (BMI), fat mass and health-related behaviours of the children. Self-reported height and weight of their parents, parental school education as a measure of social class. Results: The prevalence of overweight (greater than or equal to90th percentile of reference) was 18.5%. There was an inverse social gradient (P < 0.01): the highest fat mass was observed in children from low social class. The odds ratios for overweight reached 3.1 (CI 1.7-5.4) in boys and 2.3 (CI 1.2 -4.3) in girls, respectively (low vs high social class). Overweight parents (BMI >= 25 kg/m(2)) were more likely to have overweight children. Parental overweight enhanced the inverse social gradient. The prevalence of overweight was 37.5% (low social class) vs 22.9% (high social class) in children from overweight parents, respectively. There was an inverse social gradient in unhealthy behaviours. Parental BMI and physical inactivity were independent risk factors of overweight in children. Conclusions: In 5 to 7-y-old children overweight and health-related behaviours are inversely related to social class. Parental overweight enhanced the risk of childhood overweight. The familial effect on body weight is most pronounced in children with low social class. Preventive measures should specifically tackle 'overweight families' from low social class.