Socioeconomic Inequality in Childhood Obesity: A Comparison of the United States, the United Kingdom, and Australia

Purpose:  Childhood obesity is a major health and social welfare concern in the United States (US), and increasingly, becoming a health epidemic in other countries. It is well known that childhood obesity is correlated with numerous development issues and is a predictor of chronic illness during adulthood. Disparities that are evident in early childhood grow with age and result in unequal illness and mortality burdens later in life.  This is particularly important because there are large socioeconomic differences in obesity rates in the US, making this issue not only a public health concern but one of social welfare and inequality.

This paper uses data from three highly comparable, nationally representative child cohort studies to compare socioeconomic inequalities in childhood obesity at school entry, a critical developmental age, in Australia, the United Kingdom (UK), and the US. Previous research on child health inequalities internationally has been inconclusive—largely due to lack of comparable data. This international comparison facilitates a greater understanding of the factors driving socioeconomic inequality in child obesity through contrasting two major theoretical health inequality frameworks. First, neo-materialist theory would suggest that universal child health and social welfare programs (e.g. nurse visitors, child care, and child stipends to support nutrition) would result in lower socioeconomic inequalities in childhood obesity in Australia and the UK than in the US. Second, theory based on relative social position would suggest that obesity inequalities are equal in all three countries, despite protective social welfare and health systems in Australia and the UK.

Method: This paper uses three national datasets: The Longitudinal Study of Australian Children, the Millennium Cohort Study for the UK, and the Early Childhood Longitudinal Study for the US. The outcome variable of interest is childhood overweight/obesity at age 5 when children are entering school. Due to the country-level variation in obesity rates, different standardized childhood obesity measures are presented: BMI≥95^th percentile (CDC obesity), BMI≥85^th percentile (CDC overweight), and International Obesity Task Force cutpoint. The independent variables of interest are weighted income quintiles and parental education. A rich set of covariates are included in the models. Results are presented as weighted odds ratios.

Results: Inequality in child overweight and obesity by both income and education is greater in the US than in the UK or Australia. In the US, children in the poorest income quintile are twice as likely to be overweight than children in the top quintile (OR=1.99, p<.05). In England, poor children are at higher risk of overweight (OR=1.22, p<.05), but the relationship is weaker than in the US. Finally, in Australia, there is no difference in child overweight by income. Similar patterns are found by education.

Conclusions/Implications: We find that inequality in childhood overweight and obesity at school entry is greater in the US than in the UK and Australia. These findings provide support for the neo-materialist framework for understanding health inequalities, suggesting that universal child health initiatives may have the potential to not only reduce overall childhood obesity, but also alleviate inequalities that have lifelong health impacts.