High Pollution Levels Increase Chances of 'Silent Miscarriage': Study
Thu, April 22, 2021

High Pollution Levels Increase Chances of 'Silent Miscarriage': Study

Several studies show a connection between air pollution and miscarriage / Photo Credit: Shutterstock


Miscarriages often occur due to uterine problems and the wrong number of chromosomes present in the embryo. Women with unhealthy habits are the ones who are most at risk. Now, a new study of pregnant women in Beijing found another possible cause for miscarriage: air pollution.

A team of researchers from Chinese universities found a link between bad air quality and so-called "silent miscarriages," which occurs when a fetus fails to fully form or dies during the first trimester. They said pregnant women who are exposed to high levels of pollution are at greater risk of having a miscarriage.

The researchers published the results of the study on pregnant women in Beijing in the journal Nature Sustainability.


Air pollution and miscarriages

Beijing is currently 7.2 times above safe pollution levels based on World Health Organization (WHO) guidelines. These high levels increase the risk of miscarriage for expectant mothers living in Beijing.

The collaborative effort of various authors from several universities in China analyzed clinical records of over 250,000 pregnant women from 2009 to 2017. Among those records, they found that 6.8 percent (17,497) of the women have experienced a silent miscarriage.

They also found that the possibility of such miscarriages increased relative to higher concentrations of air pollutants, even after taking into account the women's ages, occupations, and air temperature, Deutsche Welle Akademie reports. Deutsche Welle Akademie (DW) is a Germany-based broadcaster that seeks to strengthen, develop, and set the standard for independent journalism and the human right of expression.



It adds that women who got pregnant after turning 39 years old, farmers, and blue-collar workers had a higher risk of a silent miscarriage linked to air pollution. Air would be considered polluted if it consists of four pollutants (fine particulate matter or PM 2.5, sulfur dioxide, ozone monoxide, and carbon monoxide), according to the researchers.

"The risk increase is not linear but becomes more severe the higher the pollutant concentration," the researchers said.

They calculated air quality levels based on historic data from Beijing's network of air monitoring systems. Average hourly PM2.5 reading in the Chinese capital was 42.6 micrograms per cubic meter of air in the first eight months of 2019, based on data from swiss air purification technology company IQAir's research arm AirVisual.

The results of the recent study add to the growing body of evidence indicating a correlation between air pollution and pregnancy complications.


Earlier works

PM 2.5 is among the most common air pollutants found in cities. With merely a diameter of a hair, particulate and ultrafine particulate matter are tiny enough to enter the lungs, travel through the blood vessels, and circulate in the brain.

There are numerous known harmful effects of air pollution; from respiratory illnesses to cognitive decline and possibly now, miscarriage, given a number of studies that looked into the link between the two.


According to WHO, people worldwide are breathing in high levels of pollutants / Photo Credit: Shutterstock


Research published in February found that short-term exposure to elevated levels of air pollutants increased risks of pregnancy loss by 16 percent. This study looked into the records of 1,398 women who experienced miscarriages in Utah between 2007 and 2015.

A study released last month presented new evidence that air pollution raises the possibility of future health problems for unborn children. Researchers found that breathing in black carbon pollution may allow harmful particles to make their way from the mother's lungs into the placenta.

These pollutants may eventually reach the fetuses in the womb and cause health problems both for the mother and the child, CNN reports.


The facts matter

According to the WHO, over 90 percent of people around the world are breathing in high levels of pollutants—putting nearly everyone at risk of health complications.

Air pollutants are everywhere—at home, the workplace, school—and PM is among the more complicated pollutants that government agencies, as well as health and environmental organizations, are looking to regulate to lessen their effects on public health.

These particles come from various sources, can change in shape and chemical composition, and even travel to virtually everywhere. Thousands of PM enter the human body with every breath taken—that's thousands of particles 12 to 16 times per minute every day.



Scientists estimate that PM is associated with 30,000 to 80,000 deaths in the US per year, according to the US-based nonprofit science advocacy organization Union of Concerned Scientists (UCS). It adds that these estimates are much higher compared to the combined deaths due to car accidents and gun shootings but are on par with breast cancer and diabetes deaths.

However, experts note that directly attributing death to PM exposure is more complicated than it seems. This is because the pollutant is "a trigger for other life-threatening diseases such as cardiopulmonary disease, cancer, and asthma, among others," UCS says.

But exposure to PM, as well as other pollutants, are becoming a growing concern for many cities as a majority of the global population are living in places with toxic air.