Air pollution increases risk of ‘silent’ miscarriage

In this day and era, if you're living in a city, air pollution is near inevitable. You can swear off smoking and upgrade to an electric stove, but you cannot avoid the clutches of air pollution that causes a myriad of health problems. Recently, a sinister new effect of air pollution has been revealed, and it is 'silent' miscarriage.

A "missed", or silent, miscarriage, happens when the fetus dies during the first trimester, but the body does not recognize the pregnancy loss and no symptoms like bleeding occur. High levels of air pollution appears to increase the risk of this happening. 

The study was recently carried out in Beijing, the smog-filled capital of China that has notoriously poor air quality. The findings were reported in the journal Nature Sustainability. 

Researchers from five Chinese universities analyzed the records of 255,668 women who were pregnant between 2009 and 2017, including almost 17,500 who experienced missed miscarriages. These figures were compared with levels of maternal exposure to four major air pollutants, fine particulate matter (PM2.5), sulfur dioxide, ozone, and carbon monoxide. Factors such as age and occupation were accounted for and it was found that increased levels of all four air pollutants were associated with a higher risk of missed miscarriage.

Silent miscarriages occur in up to 15 percent of all pregnancies, but they're seen more often in developing countries. This kind of miscarriage occurs when the fetus doesn't form or dies after being formed, but the placenta and embryonic tissues are still in the uterus. 

Exactly how air pollution accelerates the risk of a silent miscarriage is not clear, but this study is indeed one of many that outline the perils of being exposed to dirty city air during pregnancy. Air pollution has already been linked to increased risk of miscarriage, lower birth weight, brain abnormalities, and even a higher risk of autism. Even after the child is born, air pollution keeps causing complications such as respiratory conditions and cardiovascular diseases, including heart attacks, strokes, arrhythmia, heart failure, emphysema, and lung cancer.

Another recent study found out that soot and particulate matter from car engines and fossil fuel plants can be found in the fetal side of the placenta, meaning it might interact with or disturb fetal development. A German study from earlier this year found that air pollution is responsible for nearly 9 million premature deaths each year, almost double the number estimated by previous studies.

"To put this into perspective, this means that air pollution causes more extra deaths a year than tobacco smoking, which the World Health Organization estimates was responsible for an extra 7.2 million deaths in 2015," Thomas Münzel, co-author of the recent Germany study and a professor at the University Medical Centre Mainz, said in a statement.

"Smoking is avoidable but air pollution is not."