Dirty air and lost pregnancies in South Asia

More than 349,000 lost pregnancies each year in South Asia are linked to excessive air pollution, according to a new study in The Lancet Planetary Health journal.

The research builds on previous evidence that small particulate matter pollution (PM2.5) can harm developing fetuses. The study is the first to estimate the air pollution burden on South Asian women and suggests that the excessive pollution may be responsible for up to 7 percent of pregnancy loss in the region from 2000 to 2016.

“South Asia has the highest burden of pregnancy loss globally and is one of the most PM2.5 polluted regions in the world,” lead author, Dr. Tao Xue, a researcher at China’s Peking University, said in a statement. “Poor air quality could be responsible for a considerable burden of pregnancy loss in the region.”

Xue and colleagues collected health and household survey data from 1998-2016 from women in India, Pakistan, and Bangladesh who had at least one lost pregnancy and one livebirth. They also estimated the women’s exposure to PM2.5.

PM2.5 consists of toxic airborne particles much tinier than the width of a human hair, and is linked to a variety of health impacts including respiratory and heart problems, and altered brain development for children. It also affects proper development of the embryo in mothers’ wombs and, along with other pollutants such as carbon monoxide, has been associated with stillbirths and spontaneous abortions.

They modeled the risk for each woman for every 10 micrograms per cubic meter increase of PM2.5, and used this risk to look at the whole region from 2000 to 2016, estimating how many lost pregnancies could have been prevented with cleaner air.

Each 10 microgram per cubic meter increase in PM2.5 was linked to a 3 percent increase in the likelihood of a lost pregnancy, with the greatest risk for older women, those in rural areas, or young women from large cities. The researchers estimate for every year from 2000 to 2016 about 349,681 lost pregnancies were associated with air pollution exceeding India’s regulatory standards for PM2.5. This represents 7 percent of the total lost pregnancies in the region over that period.

When air pollution exceeded the more rigorous World Health Organization standards, such exposure was linked to 29 percent of the pregnancy losses.

“Our findings suggest that a considerable proportion of the pregnancy loss burden in South Asia is attributable to exposure to ambient PM2.5 and that improving air quality would promote maternal and infant health globally,” the authors wrote.

Previous studies have found similar associations between air pollution and lost pregnancies in California, other parts of the U.S., China, and Africa. However, there’s been less data on South Asia, even though it has the highest rate of pregnancy loss in the world. From 2010 to 2015, India, Pakistan, and Bangladesh combined for 25 percent of all babies born globally, but accounted for 35 percent (917,800) of stillbirths across the globe.

The impact goes beyond lost pregnancies—a study last month found India’s air pollution resulted in 1.67 million deaths in 2019, the largest such toll on the planet.

The new study was limited in that they weren’t able to differentiate between natural pregnancy loss and abortions, there could have been bias in women’s reporting because of stigma.

However, the implications are enormous, the authors warned, and branch into mental health problems and gender inequality.

“We know losing a pregnancy can have 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 labor,” co-author Dr. Tianjia Guan from the Chinese Academy of Medical Sciences and Peking Union Medical College, said in statement.

“Therefore, reducing pregnancy loss may also lead to improvements in gender equality.”

Banner photo: Mothers in India discuss breastfeeding. (Credit: Russell Watkins/Department for International Development)