Longitudinal influences of neighbourhood green spaces on children’s overweight

Abstract

Children overweight have been inconsistently associated with neighbourhood environment. This study examines longitudinal relationships between neighbourhood greenness levels, home distance to city parks and children overweight. Methods. This nested case-control study included 1,489 children of 4−6 year’s age who were recruited to the newborns cohort study. Questionnaire information was used to estimate children body mass index by growth charts. Individual exposure to greenness levels was assigned as the average of satellite-derived Normalized Difference Vegetation Index (NDVI) within a 500 m Euclidian buffer of each participant address, and residential distance to nearest city park was assessed by GIS. We used logistic regression models to estimate associations separately for each exposure–outcome pair, and both exposures together, adjusted for relevant covariates. Results. The lower neighbourhood greenness exposure (NDVI/parks) during pregnancy and over 4 years was associated with slightly increased children’s overweight risk. In a stratified analysis, using the high neighbourhood greenness (NDVI-500>median) and the distance to city parks (<1000 m) as a reference group, we found statistically significant increased risks for overweight for children with low neighbourhood greenness and farther distance from a park (OR 1.73, 95% CI 1.02 – 2.95). These associations were robust to adjustment for covariates associated with overweight, such as maternal education, smoking during pregnancy, chronic disease, child’s gender, low birth weight, and sedentary behaviour. Conclusions. Children’s overweight is only partially explained by unfavourable environmental factors. Low neighbourhood greenness exposure during pregnancy and later may be a risk factor of overweight throughout the developmental trajectory of childhood; therefore increasing physical activity in the green environment has been recommended as a measure