Prevalence and determinants of overweight and obesity among preschool-aged children from migrant and socioeconomically disadvantaged contexts in Montreal, Canada.

Among migrant and socioeconomically disadvantaged preschool-aged children followed in social perinatal primary care services in Montreal, Canada, we estimated the prevalence of overweight/obesity and identified determinants of body mass index z-score (zBMI) at 4-5 years old. We conducted a retrospective cohort study using electronic medical records of 275 child-mother dyads followed from birth to 4-5 years. Anthropometric measures and established maternal, perinatal and child risk factors for childhood obesity were examined. Age- and sex-specific zBMI at 4-5-years were computed and categorized according to WHO standards. Linear regression with model averaging was used to identify early life factors associated with zBMI. At 4-5 years, children's weight status was classified as underweight (1.5%), normal weight (69.7%), at-risk-of-overweight (19.2%), overweight (6.9%), and obesity (2.7%). Primiparity (0.51, 95% CI 0.24; 0.78), higher birthweight (1.04, 95% CI 0.70; 1.37), accelerated weight gain in the first year of life (0.21, 95% CI 0.13; 0.31), and introduction to solid foods before 6 months (0.89, 95% CI 0.42; 1.36) were associated with a higher zBMI, while less than high school education (-0.50, 95% CI -0.95; -0.05) and higher gestational age (-0.14, 95% CI -0.21; -0.05) were associated with lower zBMI at 4-5 years. Overweight/obesity is prevalent among preschool-aged children from migrant and socioeconomically disadvantaged contexts and is associated with known risk factors. Future research is needed to better understand the role of social perinatal primary care services in promoting optimal weight gain among children living in contexts of vulnerability.