Air Pollution and its Effect on Low Birth Weight

Abstract

Background: Environmental conditions, predominantly air pollution, are directly related to human health. Exposure to air pollutants is linked to several diseases, affecting the most vulnerable population groups, above all pregnant women and children. Air pollutant exposure has an impact on adverse birth outcomes, but studies about the effect of air pollutants on birth weight of newborns are rare. Additionally, the exact effect of air pollutants on the unborn child on cellular level have not been determined yet. Objectives: In this literature review, evaluation of air pollution and its components especially focusing on PM ≤2.5μm, PM 10μm, ozone, nitrogen dioxide, CO gas and heat are analyzed, focusing on first, second and third trimesters as well as the entire pregnancy, pointing out the main question of associations and effects of air pollution on low birth weight in newborns. The aim is to clarify the effect of air pollution on low birth weight in newborns, pointing out if some air pollutants might be more hazardous than others, analyzing if there is a phase of increased vulnerability during pregnancy, collecting and summarizing data from several studies, providing a basis for further research and studies as well as giving information for soon-to-be mothers, pregnant women and their relatives, including possible protective measures to decrease harm for mother and child. Methods: Study research was conducted via PRIMO and PubMed databases including studies from Europe, the US, Canada and China of the last ten years (2013-2023). Results: This review underlined the associations of air pollutants and low birth weight of the newborn, showing hazardous effects predominantly when the pregnant female has been exposed to PM ≤2.5μm. Also, preterm birth, small for gestational age and stillbirth are negatively associated with air pollutant exposure. Accumulation of air pollutants in placental tissues, increased oxidative stress for mother and fetus and signs of inflammation have been shown to be the most probable underlying pathological mechanisms, leading to decreased placental blood flow, impairing fetal growth, thus causing adverse birth outcomes. Conclusions: In general, air pollutants increase oxidative stress and cause inflammation leading to adverse birth outcomes. The fetus seems to be most affected throughout the entire pregnancy but being most vulnerable in the first trimester given its size. Further research is needed to understand underlying mechanisms, focusing for example on biomarkers in maternal blood.