Air pollution and pregnancy outcomes in Dhaka, Bangladesh

Abstract

• Air quality in Dhaka city remains in ‘unhealthy’ to ‘extremely unhealthy’ state for two third of the year • There is an alarming increase in the number of ‘unhealthy’ to ‘extremely unhealthy’ air days • Low birth weight (LBW) increases from 20.6% to 36.0% for the lowest and highest category air pollution exposure. • Percent preterm births (PTB) shows a linear increase from 9% to 15.2% between lowest and highest category of air pollution exposure • Female fetuses are at higher risk of LBW and male fetuses are more prone to PTB • For every 10,000 Air Quality Index (AQI) value increase in cumulative exposure, the rate of increase in LBW and PTB is 4% and 2% respectively • Second trimester could be potentially the most vulnerable period of pregnancy due to ambient air pollution Air pollution, one of the biggest environmental risks to health, is a severe problem in Bangladesh. The Lancet ‘Commission on Pollution and Health’ emphasized on the importance of research on health effects of ambient air pollution. This study explored the negative health impact of air pollution on pregnancy outcomes - preterm births (PTB) and low birth weight (LBW). The study assessed air quality in terms Air Quality Index (AQI) and, quantified the association with LBW and PTB. Pregnancy outcome data was collected from the Maternal and Child Health Training Institute in Dhaka, and the AQI data from the Clean Air and Sustainable Environment project of Department of Environment. A total 3,206 birth outcome records were assessed within the period from 2014 to 2017. Air pollution situation is quite alarming in Dhaka city, at ‘Unhealthy’ to ‘Extremely Unhealthy’ levels for two thirds 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% 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 potentially the most vulnerable period of pregnancy. Proper interventions to reduce air pollution levels need to be urgently implemented.