Air pollution may cause ‘silent’ miscarriages risk: Study

The risk of missed abortion in the first trimester increases with exposure to PM 2.5, sulfur dioxide, ozone and carbon monoxide in older women, female farmers

By DTE Staff
Published: Tuesday 15 October 2019

Air pollution has been long linked with pregnancy complication, including stillbirth and miscarriages. But, according a new study, maternal exposure to toxic pollutants in the atmosphere can potentially lead to silent miscarriages.

Pregnant woman who were exposed to air pollutants such as particulate matter (PM) 2.5, sulfur dioxide (SO2), ozone (O3) and carbon monoxide (CO) suffered missed abortion in the first trimester (MAFT) or missed miscarriage, according to the study published in the journal Nature Sustainability

MAFT occurs when a foetus stops growing or has died, but there are no physical symptoms such as bleeding or pain. It takes place before 12 weeks of gestation and women are often unaware that their pregnancy has ended.

A team of researchers from four universities — Beijing Normal University, Capital Medical University, Peking University and Tongji University — and from the Chinese Academy of Sciences analysed records of 255,668 pregnant women in Beijing from 2009 to 2017.

They examined the role of four airborne pollutants: PM2.5, SO2, O3 and CO; and found 17,497 (6.8 per cent) women experienced MAFT.

The risk of MAFT increased  with exposure to each air pollutant in women older than 39 years at conception, female farmers and blue-collared workers.

The risk of complications occurs because pollutant penetrates the placenta — the maternal-foetal blood barrier — and affects the growth and development of the foetus, the researchers explained.

“Pollutants penetrating the bloodstream of a foetus might interact with its tissue components to produce pathological effects, leading to irreversible damage to the dividing cells of the foetus and triggering hypoxic harm or immunomediated injury during critical periods of development,” according to the study.

While exposure to PM 2.5 can attack “induce alterations” in the foetus' immune system, CO can affect the metabolic and transport function of the placenta, leading to foetal hypoxia, and ultimately death of the foetus.

MAFT may occur in up to 15 per cent of all clinically recognised pregnancies, especially in developing countries. Women planning motherhood must protect themselves from air pollution exposure, the researchers suggested.

Poor air quality is also the leading cause of global disease burden and is a major factor for cardiovascular and respiratory diseases. It is also responsible for seven million premature deaths each year.

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