Increased impact of air pollution on lung function in preterm versus term infants: the BILD study

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-birth-cohort of 254 preterm and 517 term infants, we investigated associations of particulate matter (PM10) and nitrogen dioxide with lung function at 44 weeks postconceptional age and exhaled markers of inflammation and oxidative stress response (fraction of exhaled nitric oxide (FeNO)) 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 FeNO were found in term and preterm infants. Importantly, we observed stronger positive associations in preterm infants (born 32 - 36 weeks), with an increase of [184.9 (79.1, 290.7) mL/min] minute ventilation per 10 microg/m(3) increase in PM10 than in term infants [75.3 (19.7, 130.8) mL/min] (pprematurity x PM10 interaction = 0.04, after multiple comparison adjustment padj = 0.09). Associations of PM10 and FeNO differed between moderate to late preterm [3.4 (-0.1, 6.8) ppb] and term [-0.3 (-1.5, 0.9) ppb] infants, the interaction with prematurity was significant (pprematurity x PM10 interaction = 0.006, padj = 0.036). Conclusion Preterm infants showed significant higher susceptibility even to low-to-moderate prenatal air pollution exposure than term infants, leading to increased impairment of postnatal lung function. FeNO results further elucidate differences in inflammatory/oxidative stress response comparing preterms to terms.