In-utero exposure to air pollution and blood pressure in children from the Rhea birth cohort study, Greece

Abstract

BACKGROUND AND AIM: High blood pressure (BP) in childhood has been linked with hypertension and impaired cardiovascular health within adulthood. Exposure to air pollution has been associated with elevated BP in children but only a few studies evaluated the persistence of these associations into early adolescence. We investigated the association between pregnancy exposure to air pollution and BP through childhood in the Rhea birth cohort in Greece. METHODS: Residential exposure to particulate matter <10 μm (PM10) and <2.5 μm (PM2.5) during pregnancy was estimated with temporally adjusted land-use regression models. We measured systolic (SBP) and diastolic (DBP) blood pressure at 4, 6, and 11 years. Hypertension was defined as DBP or SBP ≥95th sex-, age- and height-percentiles. Generalized estimating equation and multivariate regression models assessed the associations (per 5 µg/m³) with repeated and single time-point measures, respectively. We also tested effect modification by sex and maternal smoking. RESULTS: Median (IQR) levels of PM2.5 and PM10 during pregnancy were 14.4 (2.4) μg/m3 and 35.6 (2.3) μg/m3, respectively. PM10 was associated with higher SBP and DBP in boys but lower in girls (p-interaction= 0.025 and 0.036) at 4 years. We also observed higher risk for hypertension overall (1.62; 95% CI: 1.04, 2.53) and in boys (2.01; 95% CI: 1.07, 3.79), and in children born to non-smoking mothers during pregnancy (2.14; 95% CI: 1.25, 3.66). Higher PM2.5 was associated with lower SBP in boys at 6 (β= -3.75 mmHg; 95% CI: -7.14, -0.36) and 11 years (β= -4.49 mmHg; 95% CI: -9.09, 0.11; p-interaction= 0.068 and 0.072). Sex differences in BP trajectories were also observed. CONCLUSIONS: This study suggests that prenatal air pollution exposure may affect blood pressure during childhood. Further research is needed to understand sex differences and the role of co-exposure to maternal smoking. KEYWORDS: Blood pressure, childhood, air pollution, prenatal