Introduction In 2008 the prevalence of obesity in the USA, England and Italy were 14.6%, 21.2% and 22.2%, respectively. Childhood obesity which may be more amenable to change, is a risk factor for obesity and chronic health conditions in adults.

Methods Socioeconomically disadvantaged children aged 4–7 y and their parents in Beer-Sheva were the study population in an intervention trial. We excluded those who refused, children with any chronic disease, developmental problems, in a weight reduction treatment and children or parents with any psychiatric problem. We measured twice weight and height of children and mothers in the mornings before breakfast, with light clothing and without shoes. Other data were obtained by personal interviews. Smoking and maternal perception of the child's weight status will be examined using the baseline data.

Results Overall 18.5% and 11.3% of the children were overweight and obese, respectively. Overweight/obese (OWO) children were significantly taller, heavier and had more sedentary hours than non-OWO children. Mothers misclassified the child's weight status in 82.3% and 42.4% of OWO and non-OWO children, respectively (p<0.001). In a multivariate logistic regression which included the child's sedentary hours, maternal education and weight status, poverty status, only misclassification of the child's weight status (OR 8.3, 2.7–25.9; p<0.001) and current parental smoking (OR 4.2, 1.6–11.4; p=0.005) were significant risk factors for OWO in LSES pre-school children.

Conclusions Maternal misclassification of her child's weight status and parental smoking may be determinants of the development of childhood obesity among LSES children. These associations should be confirmed in prospective studies.