Increased Impact of Air Pollution on Lung Function in Preterm versus Term Infants: The BILD Study

Abstract

Rationale: Infants born prematurely have impaired capacity to deal with oxidative stress shortly after birth. Objectives: We hypothesize that the relative impact of exposure to air pollution on lung function is higher in preterm than in term infants. Methods: In the prospective BILD (Basel-Bern Infant Lung Development) birth cohort of 254 preterm and 517 term infants, we investigated associations of particulate matter ⩽10 μm in aerodynamic diameter (PM₁₀) and nitrogen dioxide with lung function at 44 weeks' postconceptional age and exhaled markers of inflammation and oxidative stress response (fractional exhaled nitric oxide [Fe_NO]) in an explorative hypothesis-driven study design. Multilevel mixed-effects models were used and adjusted for known confounders. Measurements and Main Results: Significant associations of PM₁₀ during the second trimester of pregnancy with lung function and Fe_NO were found in term and preterm infants. Importantly, we observed stronger positive associations in preterm infants (born 32-36 wk), with an increase of 184.9 (95% confidence interval [CI], 79.1-290.7) ml/min [Formula: see text]e per 10-μg/m³ increase in PM₁₀, than in term infants (75.3; 95% CI, 19.7-130.8 ml/min) (p_{prematurity × PM10 interaction} = 0.04, after multiple comparison adjustment p_adj = 0.09). Associations of PM₁₀ and Fe_NO differed between moderate to late preterm (3.4; 95% CI, -0.1 to 6.8 ppb) and term (-0.3; 95% CI, -1.5 to 0.9 ppb) infants, and the interaction with prematurity was significant (p_{prematurity × PM10 interaction} = 0.006, p_adj = 0.036). Conclusions: Preterm infants showed significantly higher susceptibility even to low to moderate prenatal air pollution exposure than term infants, leading to increased impairment of postnatal lung function. Fe_NO results further elucidate differences in inflammatory/oxidative stress response when comparing preterm infants with term infants.

Keywords: chronic obstructive pulmonary disease; nitrogen dioxide; particulate matter; premature infants; prenatal injuries.