By Disha Shetty, Jan. 8, 2021
Pregnant women in India, Pakistan and Bangladesh, who are exposed to polluted air may be at a higher risk of stillbirths and miscarriages, according to a modelling study published in the peer-reviewed journal Lancet Planetary Health. Improving air quality could cut down the risk of miscarriages and stillbirths, the study found.
The modelling study estimated that nearly 349,681 pregnancy losses per year in the three countries in south Asia were associated with exposure to PM2.5, in concentrations that exceeded India’s air quality standard (more than 40 μg/m³). These losses accounted for 7% of annual pregnancy loss in the region between 2000-2016.
PM2.5 are tiny particles or droplets that are roughly thirty times smaller in width than an average human hair. The particles can travel deep into the respiratory tract and reach the lungs, worsening medical conditions such as asthma and heart disease.
If the countries met the more stringent (10 μg/m3) air pollution standards set by the World Health Organization’s (WHO), nearly 29.7% pregnancy losses could be avoided, the study estimated.
“Our findings suggest that poor air quality could be responsible for a considerable burden of pregnancy loss in the region, providing further justification for urgent action to tackle dangerous levels of pollution," said Tao Xue of Peking University, China, who is the lead author of the study.
Mounting evidence of air pollution – reproductive health link
Increasing number of studies are now linking air pollution to maternal and child health. A report by Health Effects Institute (HEI) estimated that in 2019 indoor and outdoor air pollution contributed to nearly 500,000 infant deaths globally. This is the first such study to quantify the burden between air pollution and pregnancy loss in south Asia.
"We know losing a pregnancy can have knock-on mental, physical and economic effects on women, including increased risk of postnatal depressive disorders, infant mortality during subsequent pregnancy, and increase the costs related to pregnancy, such as loss of labour. Therefore, reducing pregnancy loss may also lead to knock-on improvements in gender equality," said co-author of the study Tianjia Guan from the Chinese Academy of Medical Sciences and Peking Union Medical College.
In India alone losses linked to the public health impacts of air pollution is estimated to have cost the economy $36.8 billion.
Loss more in Indo-Gangetic plain
For this study authors used data from household surveys in the three countries. There were 34,197 women who had lost a pregnancy, including 27,480 miscarriages and 6,717 stillbirths, which were compared to livebirth controls. Of the pregnancy loss cases, 77% were from India, 12% from Pakistan, and 11% from Bangladesh.
Researchers estimated exposure to PM2.5 during pregnancy by combining satellite with atmospheric modelling outputs. They found that the pregnancy loss associated with air pollution was more common in the northern plain region in India and Pakistan.
The authors cautioned that there were limitations to the study as there were data gaps, including under-reporting of pregnancy losses because of stigma or ignoring very early pregnancy losses. They also relied on satellite-based estimates of air pollution to compensate for insufficient local monitoring.