Associations of area characteristics at birth with overweight and obesity among school-aged children in the south of England: an analysis of a population-based cohort

Abstract

BackgroundGeographical inequalities in the prevalence of overweight and obesity among children are well established in cross-sectional research. We aimed to examine how area-level characteristics at birth are related to these outcomes in childhood. MethodsAnonymised antenatal and birth data recorded by University Hospital Southampton (2003–18) linked to school-measured weight and height data for children within Southampton, UK were used (14 084 children at ages 4–5 years, and 5 637 at ages 10–11 years). Children's home address at birth was provided at the lower layer super output area level (areas with average populations of 1500). Area-level indices (walkability, unhealthy or healthy food outlets, and spaces for social interaction), natural greenspace coverage, supermarket density, and measures of air pollution (PM2·5, PM10, and NOx) were constructed for lower layer super output areas using data from Ordnance Survey and open sources. Overweight or obesity was defined as a BMI greater than the 85th centile for sex and age. Population-average generalised estimating equations estimated the risk of being overweight or obese for children at both time points. Confounders accounted for included maternal BMI and smoking in early pregnancy, educational attainment, ethnicity, and parity. This project was approved by the NHS Health Research Authority (242031). FindingsNo significant associations were noted between area characteristics at birth and overweight or obesity at ages 4–5 years. The proportion of the lower layer super output area covered by greenspace was negatively associated with the risk of being overweight or obese at ages 10–11 years (relative risk ratio 0·997, 95% CI 0·995–0·999). This finding was consistent in a subgroup of children who moved residence (between different lower layer super output areas) between birth and time of measurement. InterpretationLocal access to natural greenspaces at the time of birth was negatively associated with becoming overweight or obese by the end of primary school, regardless of migration. However, the size of this protective effect is small. Access to and protection of greenspace might have a role in early prevention of childhood obesity. FundingSupported by an Academy of Medical Sciences and Wellcome Trust grant to NAA and the National Institute for Health Research through the NIHR Southampton Biomedical Research Centre.