Urban Environment and Growth and Obesity in Preschool Children from Six European Birth Cohorts

Abstract

BACKGROUND AND AIM: Urban environmental exposures have been investigated separately in relation to growth and childhood obesity. In this study we aim to determine which prenatal and postnatal outdoor exposures are associated with childhood BMI, weight and height at age 3-4 years. METHODS: Height and weight were measured in 11,325 children aged 3-4 years from a multi-centre European cohort (France, Greece, Lithuania, Norway, Spain, and UK). BMI was calculated using the formula weight/height². Age-and-sex–standardized {z}-scores were calculated for height, weight and BMI. Urban environment exposures were estimated during pregnancy and childhood, including air pollution, built environment, green spaces, traffic, noise, meteorology, and socioeconomic deprivation index. Exposure-wide association study was performed using multiple single exposure linear regression models and accounting for multiple testing. RESULTS:Non linear associations were observed between exposure to Normalized Difference Vegetation Index (NDVI), a measure of greeness, and the outcomes leading to its categorization into tertiles. Pregnancy and postnatal NDVI in the first tertile were associated with greater height compared to the reference (second tertile), and remained statistically significant after correction for multiple testing (prenatal corrected {p}-value threshold for significance = 0.002; postnatal corrected {p}-value = 0.003). Other prenatal and postnatal markers of the urban environment such as walkability, building density and land use, nitrogen dioxide and fine particles were also associated with greater height, but were no longer statistically significant after correction for multiple testing. Fine particles during pregnancy were associated with higher BMI, and prenatal NDVI in the first tertile and air pollution were also associated with higher weight, but the {p}-values for these associations were above the corrected threshold for multiple testing. CONCLUSIONS:Living in a less green and more densely built and walkable area may affect preschool height in a positve manner. KEYWORDS: External exposome, Green space, Built environment, Children's environmental health, Obesity and metabolic disorders