Particulate air pollution and birth weight: A systematic literature review

Purpose: An increased number of studies have been published on the adverse effects of ambient air pollution on birth outcomes. The aim of this review is to identify and update the growing body of literature of epidemiological evidence on the association of ambient particulate matter (PM) and term birth weight and explore the determinants that may affect the vulnerability of exposure to air pollution. Methods: We systematically searched Web of Knowledge and PubMed for English-language studies published in peer review journals up to October 2018. Eligible studies were those investigating exposure to ambient particulate air pollution measured as PM2.5 (aerodynamic diameter <= 2.5 mu m), PM10 (aerodynamic diameter <= 10 mu m), PM2.5-10 (aerodynamic diameter from 2.5 to 10 mu m), ultrafine particles, TSP (Total Suspended Particulates), black smoke, black carbon or any related measure of PM addressing the impact of particulate air pollution on term birth weight outcomes. Results: A total number of 84 studies met the inclusion criteria. Most types of particulates were associated with low birth weight and particularly with decreases in term birth weight, but there were many inconsistencies in the included studies. Conclusion: Future research should focus on understanding which chemical constituents and sources of PM are associated with term low birth weight, elucidating the biological pathways that underline the associations between maternal exposure to air pollution and neonatal health, as well as considering potential effect modification by characteristics of the built environment, such as proximity to traffic and green spaces. Establishing similar guidelines among research design in studies will promote comparability of published results.