Air pollution exposure during pregnancy: maternal asthma and neonatal respiratory outcomes

Maternal asthma increases adverse neonatal respiratory outcomes, and pollution may further increase risk. Air quality in relation to neonatal respiratory health has not been studied.

Transient tachypnea of the newborn (TTN), asphyxia, and respiratory distress syndrome (RDS) were identified using medical records among 223,375 singletons from the Consortium on Safe Labor (2002-2008). Community Multiscale Air Quality models estimated pollutant exposures. Multipollutant Poisson regression models calculated adjusted relative risks of outcomes for interquartile range increases in average exposure. Maternal asthma and preterm delivery were evaluated as effect modifiers.

TTN risk increased after particulate matter (PM) less than or equal to 10-micron exposure during preconception and trimester one (9-10%), and whole-pregnancy exposure to PM less than or equal to 2.5 microns (PM_2.5; 17%) and carbon monoxide (CO; 10%). Asphyxia risk increased after exposure to PM_2.5 in trimester one (48%) and whole pregnancy (84%), CO in trimester two and whole pregnancy (28-32%), and consistently for ozone (34%-73%). RDS risk was associated with increased concentrations of nitrogen oxides (33%-42%) and ozone (9%-21%) during all pregnancy windows. Inverse associations were observed with several pollutants, particularly sulfur dioxide. No interaction with maternal asthma was observed. Restriction to term births yielded similar results.

Several pollutants appear to increase neonatal respiratory outcome risks.