Acute air pollution exposure and NICU admission: a case-crossover analysis

Abstract Background Neonatal intensive care unit (NICU) admission rates have increased over time. Air pollution is associated with adverse pregnancy outcomes but the relationship between prenatal air pollution exposure and NICU admission has not been investigated. Methods In the Consortium on Safe Labor (2002-08), 27,189 singletons were admitted into the NICU. Modified Community Multiscale Air Quality models estimated exposures for criteria air pollutants and constituents of particles ≤2.5 microns (PM 2.5 ). Case-crossover analyses calculated odds ratios and 95% confidence intervals for interquartile range increases in pollutant exposure, comparing exposures during the week of delivery to control periods before and after delivery. Results In models that adjusted for PM 2.5 , exposure to PM 2.5 constituents during the week prior to delivery were significantly associated with increased odds of NICU admission: elemental carbon (35%), ammonium ions (37%), nitrate compounds (16%), organic compounds (147%), and sulfate compounds (35%). Odds were also significantly increased by day of and day prior to delivery exposures to carbon monoxide (4-5%), nitrogen dioxide (13%), nitrogen oxides (4-8%), particles ≤10 microns (2%), particles ≤2.5 microns (2%) and sulfur dioxide (3-6%). No associations were observed for ozone. Conclusions Acute exposures to PM 2.5 constituents and several traffic-related pollutants during the week prior to delivery, the day of delivery, and day prior to delivery appear to increase the odds of NICU admissions. These novel associations suggest infants exposed in utero to common air pollutants may require additional care during the newborn hospital admission.