Prenatal exposure to ambient air pollution and adverse pregnancy outcomes in Ahvaz, Iran: a generalized additive model.

Objective: There is some evidence about the short-term effects of air pollutants on adverse pregnancy outcomes. The aim of this study was to determine the association between air pollutants and spontaneous abortion, stillbirth, gestational hypertension, preeclampsia, gestational diabetes and macrosomia in Ahvaz, which is one of the most polluted cities in the Middle East.
Methods: Data on adverse pregnancy outcomes and air pollutants including ozone (O ₃ ), nitric oxide (NO), nitrogen dioxide (NO ₂ ), sulfur dioxide (SO ₂ ), carbon monoxide (CO), particles with a diameter of less than 10 µm (PM ₁₀ ) and particles with a diameter less than 2.5 µm (PM _2.5 ) were inquired from the Health Department of Ahvaz Jundishapur University of Medical Sciences and the Environmental Protection Agency of Khuzestan Province for the years 2008-2018. A time series analysis using the generalized additive model (GAM) with up to 6-day lags was used.
Results: The results showed that the SO ₂ pollutant on 0, 1, 3, 4, and 6-day lags and PM ₁₀ on lag 0 had direct and significant associations with spontaneous abortion. NO, NO ₂ and CO on 0-6-day lags, and O ₃ on 6-day lags showed direct and significant associations with preeclampsia. NO and NO ₂ pollutants showed significant and direct associations with gestational diabetes, during 0- and 6-day lags. NO on 0-, 3- and 4-day lags, CO in all 0-6-day lags and PM _2.5 on 1-, 3-, 5-, and 6-day lags showed direct and significant associations with macrosomia. None of the pollutants showed significant associations with stillbirth or gestational hypertension.
Conclusions: The results of this study suggest that some air pollutants are associated with spontaneous abortion, preeclampsia, gestational diabetes and macrosomia. This study further emphasizes the need to control ambient air pollution.