RESEARCH ARTICLE BMI, waist circumference

is available at the end of the articleBackground Lung diseases contribute substantially to mortality [1]. Lung function deficits in childhood may increase the risk of lung diseases later in life. Smoking parents, genetic predisposition and air pollution have been shown to negatively influence children’s lung function [2,3]. A rela-tively new potential risk factor for lower lung function in children is overweight. In adults, being overweight, measured by BMI, is associated with reduced lung func-tion [4-8]. In children, the prevalence of overweight has increased considerably but studies in children on the asso-ciation between overweight and lung function show in-consistent results. In contrast to studies in adults, most studies in children seem to suggest a positive association [9-13] rather than an inverse association [14] between BMI and forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1). The observation of different directions of the association of BMI with lung function between adults and children suggests that the associatio