Is obesity a risk factor for childhood asthma?

Background: In adolescents and adults, an association between obesity and a sthma was found in females. Does this sex-specific association already exis t in young children? Methods: Questionnaire data on 9357 5- and 6-year-old German children were collected in 1997 in two rural regions in Bavaria. The diagnosis of asthma, hay fever, and eczema was ascertained with the ISAAC core and other valida ted questions. Overweight was defined by a BMI of > 90th and less than or e qual to 97th percentile and obesity by a BMI of >97th percentile. Results: The lifetime prevalence of doctor's diagnosed asthma in girls was 3.5% (95% CI 2.9-4.1%) for normal weight, 5.8% (95% CI 3.2-8.4%) for overwe ight, and 10.3% (95% CI 5.3-15.2%) for obesity, whereas no relation to weig ht was found in boys. Hay fever and eczema were unrelated to weight in girl s and boys. The adjusted odds ratio for asthma in girls was 2.12 (95% CI 1. 22-3.68) for overweight and 2.33 (95% CI 1.13-4.82) for obesity. Conclusions: A sex-specific association with doctor's diagnosed asthma was also observed in girls at school entry. Since this association was confined to doctor's diagnosed asthma in the absence of other atopic conditions, an d no association with other atopic manifestations was found, we hypothesize that this association is related to factors other than atopic sensitizatio n.