Impact of Ambient Air Pollution Exposure during Pregnancy on Adverse Birth Outcomes

Abstract

Background Air pollution exposure adversely affects birth outcomes. The study aimed to investigate the impact of ambient air pollution exposure during pregnancy adjusting prenatal risk factors on adverse birth outcomes among pregnant women in MACE birth cohort. Methods Data for the study was obtained from the Mother and Child in the Environment birth cohort (MACE) study in Durban, South Africa from 2013 to 2017. Land use regression models were used to determine household level prenatal exposure to PM2.5, SO2 and NOx. Six hundred and fifty-six births of pregnant females selected from public sector antenatal clinics. We employed a Generalized Structural Equation Models with a complementary log-log-link specification which allowed multiple simultaneous equations and decomposition of the direct and indirect effects. Results After adjustment for prenatal factors, the results indicated that exposure to PM2.5 was found to have both significant direct and indirect effects on the risk of adverse birth outcomes. Similarly, an increased level of maternal exposure to SO2 during pregnancy was associated with an increased probability of being small for gestational age. Moreover, preterm birth showed a strong effect on low birthweight and SGA and act a mediating role on the relationship of exposure to PM2.5, and SO2 with low birth weight and SGA. The findings also demonstrated that smoking, positive HIV status, and following junk foods dietary pattern of mothers were associated with increased risk of preterm birth. However, NOx showed inconsistent, protective direct and weak indirect adverse, effect on adverse birth outcomes. Conclusions Prenatal exposure to PM2.5 and SO2 pollution effects on adverse birth outcomes even after controlling for other risk factors, which were also associated with these outcomes. This suggests that health care providers should be informed about the risks of air pollution in order to aware pregnant women about limiting exposure to poor air quality.