Parental Country of Birth and Socioeconomic Disadvantage in Childhood Overweight and Obesity: Evidence From the Growing Healthy Kids Study.

Introduction: SES is a key factor influencing childhood overweight and obesity, but the impact of parents' country of birth on this link remains uncertain. This study explored how parents' country of birth affects the association between family SES-measured by area-level disadvantage and annual household income-and childhood obesity. Methods: Data were obtained from the Growing Healthy Kids population health survey (2018), which included 1,815 children aged 5-16 years. Overweight and obesity were classified using International Obesity Task Force BMI cut offs. SES was assessed through the Index of Relative Socioeconomic Disadvantage and self-reported annual household income. Multinomial mixed-effects models calculated the ORs and 95% CIs for overweight and obesity, stratified by parental country of birth (Australian born versus overseas born), while adjusting for demographic and behavioral covariates. Results: Children from the most disadvantaged areas faced a higher risk of obesity, regardless of whether their parents were Australian born (OR=1.83 [99% CI=1.70, 1.97]) or overseas born (OR=1.57 [99% CI=1.45, 1.70]). Children of Australian-born parents with household income <$52,000 also experienced a higher risk: OR=3.36 (99% CI=3.06, 3.52). Results for overweight status varied across SES measures and country of birth groups. Children of parents born in Australia and living in moderately disadvantaged areas had a higher risk of being overweight (OR=1.36, 99% CI=1.29, 1.49), whereas those living in the most disadvantaged areas had a lower risk. Children of parents born overseas and living in the most and moderately disadvantaged areas had a higher risk of being overweight (OR=1.19, 99% CI=1.08, 1.32; OR=1.42, 99% CI=1.30, 1.62). Children of overseas-born parents with a household income of $78000-$103,999 had a higher risk of being overweight (OR=1.23, 99% CI=1.13, 1.35). Conclusions: SES remains a strong predictor of childhood obesity, regardless of the parents' country of birth status. However, patterns for being overweight differ depending on the SES measure used. Area-level SES measures, such as the Index of Relative Socio-Economic Disadvantage; residents' postcodes; and individual SES measures, such as annual household income, can be incorporated into initial assessments in both clinical and population programs. They can be used to develop area-specific tailored interventions, including targeted health promotion initiatives, case management services, and practical support for those in need.