Ambient air pollution and pregnancy outcomes: a review of the literature

Thesis Abstract

Ambient air pollution has been a growing concern due to its potential impacts on pregnancy outcomes. This review aims to summarize the existing literature on the relationship between ambient air pollution and various pregnancy outcomes. The review includes studies that have investigated the effects of different air pollutants such as particulate matter (PM), nitrogen dioxide (NO2), sulfur dioxide (SO2), carbon monoxide (CO), and ozone (O3) on pregnancy outcomes including preterm birth, low birth weight, and birth defects. Studies have shown consistent associations between exposure to air pollution during pregnancy and adverse outcomes such as preterm birth and low birth weight. The mechanisms through which air pollution may affect pregnancy outcomes include oxidative stress, inflammation, and placental dysfunction. Additionally, air pollution exposure during pregnancy has been linked to an increased risk of birth defects, although more research is needed to establish causality. Particulate matter, especially fine particles (PM2.5), has been extensively studied in relation to pregnancy outcomes. Several studies have reported positive associations between PM2.5 exposure during pregnancy and adverse outcomes such as preterm birth and low birth weight. Nitrogen dioxide, a common traffic-related pollutant, has also been linked to adverse pregnancy outcomes, with some studies reporting increased risks of preterm birth and low birth weight with higher NO2 exposure. Sulfur dioxide and carbon monoxide, primarily derived from industrial sources and vehicle emissions, have been less studied in relation to pregnancy outcomes. Limited evidence suggests potential associations between SO2 exposure and adverse pregnancy outcomes, although more research is needed to confirm these findings. Similarly, the evidence on the effects of carbon monoxide on pregnancy outcomes is scarce and inconsistent. Ozone, a secondary pollutant formed by chemical reactions in the atmosphere, has been associated with adverse respiratory outcomes but its effects on pregnancy outcomes are less well-established. Some studies have reported positive associations between ozone exposure during pregnancy and adverse birth outcomes, while others have found no significant effects. In conclusion, ambient air pollution is a complex mixture of pollutants that may have detrimental effects on pregnancy outcomes. While existing evidence suggests that exposure to air pollution during pregnancy is associated with an increased risk of adverse outcomes such as preterm birth, low birth weight, and birth defects, more research is needed to elucidate the underlying mechanisms and establish causality. Efforts to reduce air pollution levels and protect pregnant women from exposure are crucial for promoting healthy pregnancies and improving birth outcomes.