Socio-demographic and behavioural risk factors associated with the high prevalence of overweight and obesity in Portuguese children

47 48 Objectives: Childhood obesity is a public health concern in Portugal. Socio-demographic and 49 behavioural factors are highly associated with obesity but are not clearly understood. This paper 50 aims to update the prevalence of overweight and obesity in Portuguese children and to explore 51 the influence and risks of socio-demographic factors and behavioural factors. 52 53 Methods: A cross-sectional study of Portuguese children aged 3-10 years from all 18 mainland 54 districts took place between March 2009 and January 2010. 17,136 (8455 boys; 8681 girls). 55 Height, weight and other anthropometric measurements were obtained by trained technicians. 56 Body Mass Index (BMI) was calculated along with other anthropometric variables. Data 57 analyses took place between April and September 2012. The overweight/obesity classification 58 was established by age-and sex-specific BMI cut-off points as defined by the International 59 Obesity Task Force (IOTF). Parents completed questionnaires about socio-demographic and 60 behavioural characteristics of the family. 61 62 Results: Almost 28% of the Portuguese children were overweight or obese (19.7% overweight; 63 8.2% obese). Prevalence was greater in girls than in boys. Logistic regression models found that 64 the odds of childhood obesity were significantly affected by biological, socio-demographic and 65 behavioural factors. 66 67 Conclusions: The protective factors against childhood overweight/obesity in this sample of 68 Portuguese children are: i) being male; ii) having been breastfeed; iii) having been born from 69