Chronic exposure to air pollution and risk of mental health disorders complicating pregnancy.

Abstract Background Air pollution is associated with mental health in the general population, but its influence on maternal mental health during pregnancy has not been assessed. Objective We evaluated the relationship between unspecified mental disorders complicating pregnancy and depression with average air pollution exposure during 3-months preconception, first trimester and whole pregnancy. Methods Ambient air pollution was derived from a modified Community Multiscale Air Quality model and mental health diagnoses were based on electronic intrapartum medical records. Logistic regression models assessed the odds of unspecified mental disorder complicating pregnancy (n=11,577) and depression (n=9,793) associated with an interquartile range increase in particulate matter (PM) less than 2.5μm (PM2.5), PM10, carbon monoxide (CO), nitrogen dioxide (NO2), nitrogen oxide (NOx), sulfur dioxide (SO2), and ozone (O3). Pregnancies without mental health disorders were the reference group (n=211,645). Models were adjusted for maternal characteristics and study site; analyses were repeated using cases with no additional mental health co-morbidity. Results Whole pregnancy exposure to PM10, PM2.5, NO2, and NOx was associated with a 29% to 74% increased odds of unspecified mental disorders complicating pregnancy while CO was associated with 31% decreased odds. Results were similar for depression: whole pregnancy exposure to PM10, PM2.5, NO2, and NOx was associated with 11% to 21% increased odds and CO and O3 were associated with 16% to 20% decreased odds. SO2 results were inconsistent, with increased odds for unspecified mental disorders complicating pregnancy and decreased odds for depression. While most findings were similar or stronger among cases with no co-morbidity, PM2.5 and NOx were associated with reduced risk and SO2 with increased risk for depression only. Discussion Whole pregnancy exposure to PM10, PM2.5, NO2, and NOx were associated with unspecified mental disorder complicating pregnancy and depression, but some results varied for depression only. These risks merit further investigation.