Breathing polluted air may put women at greater risk of miscarriage, Chinese study finds

17-Oct-2019 Intellasia | South China Morning Post | 6:02 AM Print This Post

Smog clouding Beijing’s skies is not only damaging people’s lungs breathing polluted air may also put pregnant women at greater risk of having miscarriages, a new study has found.

The research by Chinese scientists, published on Monday in the journal Nature Sustainability, examined data from more than 255,000 pregnant women living in the capital over an eight-year period.

Researchers found a significant correlation between pollution levels and “missed abortion” in the first trimester, a common form of miscarriage that can go undiagnosed for weeks.

The risk of such a miscarriage, where a fetus or embryo will stop developing, increases sharply with higher concentrations of air pollutants, they found.

The findings add to a growing body of global research linking pollution to birth defects and pregnancy complications. It also adds maternal and fetal health to the list of outcomes connected to air pollution including lung cancer, heart disease and stroke, as well as a general rise in deaths and hospital care. But for many mothers in China, the findings just confirm concerns they already had about the potential impact of smog on their unborn children.

Among them is 35-year-old new mother Yao Yuan, who found herself becoming “borderline paranoid” during her pregnancy in Shanghai.

“I was checking the AQI [air quality index] constantly. I would stay indoors, and even wear 3M masks indoors sometimes, on the bad days. Seeing the colours red or purple on my AQI app was one of the most upsetting things for me,” she said, referring to the colour coding for bad pollution days.

“There was a lot of frustration and helplessness. I felt like I couldn’t protect my future baby,” said Yao, who had a healthy birth last year.

These concerns, and the findings from the latest study, come as China’s central government is carefully watching and looking for ways to boost its historically low birth rate, with the country facing a potential economic slowdown amid a rapidly ageing population.

The report, funded by three of China’s national science foundations, explicitly addresses this social problem, noting the importance for women to protect themselves from air pollution exposure and for the country to “reduce ambient air pollution for the sake of enhancing the birth rate”.

“Fetal health affects the fate of a family and even a country,” Jintai Lin, one of the lead researchers and an associate professor with the department of Atmospheric and Oceanic Sciences at Peking University told China Science Daily.

Conducted in Beijing, a city notorious for its hazy skies, the study took into account the localised air quality indicators for pregnant women’s homes and workplaces, generating a more complete picture of daily exposure since air quality can vary widely across the sprawling capital.

Of the pregnant women taking part in the study from 2009 to 2017, 17,500 or roughly 7 per cent had a missed abortion in their first trimester, a miscarriage that can occur in up to 15 per cent of pregnancies.

While a correlation between air pollution and miscarriage was found across all surveyed demographics, pregnant women in blue-collar or agricultural jobs, and women over 39, experienced the heaviest impact from air pollutants, according to the researchers. “In China, farmers and blue-collar workers usually had a low socioeconomic status and engage in outdoor work. Female farmers or female blue-collar workers were more exposed to ambient air pollution and thus subjected to… a higher [missed abortion in the first trimester] risk than office workers,” the study said.

The findings add to international research that has connected polluted air with a range of negative effects on birth outcomes and sexual health. Previous studies have linked long-term exposure to air pollution to chromosomal abnormalities in mothers, which can increase the chances of still births or birth defects.

Tiny breathable particulate matter PM2.5 has also been found to cause direct harm to a developing fetus, and research has shown that the immune functions of the womb can also be affected by the toxins, while carbon monoxide may interfere with the natural functions of the placenta.

Another study finding was that when Beijing rolled out new rules to reduce air pollution in 2013 including shutting coal plants and taking old cars that did not meet standards off the roads the risk of miscarriage among pregnant women also dropped.

Such measures have improved air quality in Beijing in recent years PM2.5 readings fell 12.1 per cent from 2017 to 2018, though they are still five times the levels recommended by the World Health Organization.

But dozens of Chinese cities had more severe levels of air pollutants carbon monoxide and nitrogen dioxide than Beijing, according to the latest monthly statistics, for July, released by the Ministry of Ecology and Environment.

The researchers concluded that learning more about how these chemicals impact health was an important pursuit, a point Lin also emphasized.

“Researching the relationship between missed abortion and the environment is only the beginning,” he told China Science Daily.

The study authors noted that the research was not exhaustive and did not account for other factors like traffic-related noise, tobacco smoke or indoor pollution data.


Category: China

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