Increasing social disparities in obesity among 15 000 pre-schoolers in a German district from 2009 to 2019

Background Although childhood obesity prevalence has stagnated in many high-income regions after decades of increase, it continues to be a major public health problem with adverse effects. The objective was to examine obesity trends as a function of parental social status to identify obesity disparities among children. Methods Data from school entry examinations from 2009 to 2019 of 14 952 pre-schoolers in one German district were used. Logistic regression models (obesity/overweight as dependent variable) and a linear regression [BMI z-score (BMIz) as dependent variable] were performed adjusted for social status and sex to investigate time trends in overweight and obesity. Results Overall, we found an increase of obesity over time [odds ratio (ORs): 1.03 per year, 95% CI: 1.01-1.06]. Children with low social status had an OR of 1.08 per year (95% CI: 1.03-1.13), while the trend was less expressed in children with high social status (OR: 1.03 per year, 95% CI: 0.98-1.08). The mean BMIz decreased per year (regression coefficient -0.005 per year, 95% CI: -0.01 to 0.0) when considering all children. This decrease was more pronounced in children with high social status (regression coefficient: -0.011 per year, 95% CI: -0.019 to -0.004), compared with a slight increase of 0.014 (95% CI: -0.003 to 0.03) per year among children with low social status. Also, children with low parental social status were heavier and smaller than their peers with high social status. Conclusions Although the mean BMIz decreased among pre-schoolers, obesity prevalence and status-related inequity in obesity prevalence increased from 2009 to 2019 in the region studied.