Urban environment during early-life and blood pressure in children

Abstract

Background. The urban environment is characterised by many exposures that may influence hypertension development, but studies evaluating multiple urban exposures from pregnancy onwards are lacking. Methods. Using a sample of 4,279 children enrolled in four European mother-child cohorts, associations between urban environmental factors and systolic and diastolic blood pressure (BP) measured at 4-5 years old were evaluated. The urban environment was characterized during pregnancy and childhood and included air pollution, built environment, natural spaces, traffic, noise, meteorology, and socioeconomic deprivation. Single- and multiple-exposure linear regression models adjusted for potential confounders were performed, together with a cluster analysis to identify groups of mother-child pairs sharing similar exposure patterns. Results. In multiple-exposure models (considering 27 prenatal and 30 postnatal exposures), higher BP, in particular diastolic BP, was observed in association with higher exposure levels to air pollution, noise and ambient temperature during pregnancy, and with higher exposure levels to air pollution and higher building density during childhood (e.g., mean BP change [95% confidence interval] for an interquartile range increase in prenatal NO2=0.9mmHg[0.4;1.3]). Lower BP was observed in association with higher temperature the day before the BP measurement and better transport connectivity during childhood (e.g., postnatal temperature=-1.6[-2.2;-0.9]). The cluster analysis identified six clusters of mother-child pairs, among which two clusters represented a more harmful urban environment during pregnancy and childhood: one with higher air pollution, traffic and noise exposures, and the other with higher air pollution, greater urbanisation and lack of green spaces. Compared to the cluster representing the least harmful urban environment, these were both associated with higher diastolic BP (1.3[0.1;2.6] and 1.5[0.5;2.5]). Conclusion. This longitudinal study suggests that the urban environment, from the prenatal period onwards, may impact BP regulation in children. These findings reinforce the importance of designing cities that promote healthy environments to reduce long-term risk of cardiovascular diseases.