Air pollution and pregnancy outcomes in Dhaka, Bangladesh

Introduction: Air pollution, one of the biggest environmental risks to health, is a severe problem in Bangladesh. The Lancet "Commission on Pollution and Health" emphasized the importance of research on health effects of ambient air pollution. This study explored the negative health impacts of air pollution on pregnancy outcomes - preterm births (PTB) and low birth weight (LBW). Methods: The study assessed air quality in terms Air Quality Index (AQI) and quantified the association with LBW and PTB. Pregnancy outcome data were collected from the Maternal and Child Health Training Institute in Dhaka, and the AQI data from the Clean Air and Sustainable Environment Project of the Department of Environment. A total 3,206 birth outcome records were assessed within the period from 2014 to 2017. Results: Air pollution levels are alarmingly high in Dhaka, with ‘Unhealthy’ to ‘Extremely Unhealthy’ levels for almost half of the year. An increase in the prevalence of LBW and PTB was found with increasing cumulative air pollution exposure. LBW increased from 20.6% to 36.0% and PTB increased from 9.0% to 15.2% respectively between the lowest and highest category AQI value exposure. For every 10,000 AQI value increase in cumulative exposure, LBW and PTB increased by 4% and 2%, respectively. There is significant gender differentiated impact on LBW and PTB due to air pollution where female fetuses are at higher risk of LBW and males are more prone to PTB. Air pollution exposure during the second trimester increased LBW and PTB more compared to first and third trimesters, suggesting it is potentially the most vulnerable period of pregnancy. Conclusion: Air pollution contributes to adverse pregnancy outcomes. To reduce this effect, proper interventions to reduce air pollution levels need to be urgently implemented.