Northern plains region in India and Pakistan most impacted, meeting India’s air quality standard would have reduced loss by 7 per cent
Pregnant women in India, Pakistan and Bangladesh exposed to poor-quality air may be at higher risk of stillbirths and miscarriages, according to a study published in the Lancet Planetary Health journal January 6 2020.
Some 349,681 pregnancies were lost every year in these three South Asian countries due to exposure to particulate matter (PM) 2.5 concentrations that exceeded India’s air quality standard — more than 40 micro gram per cubic metre ( μg/m³) — estimated the study led by Dr Tao Xue, Peking University.
This accounted for 7 per cent of annual pregnancy losses in the region between 2000 and 2016, said the modelling study.
However, if World Health Organisation's (WHO) PM2.5 limit of 10 μg/m³ is considered, the exposure to toxic air accounted for a much higher loss of pregnancies — 29.2 per cent — in the three countries.
The estimates were made based on an assessment of data from household surveys on health from 1998 to 2016. It included data from 34,197 mothers who had at least one pregnancy loss and one or more livebirth. Of them 26,282 or 76.9 per cent were from India, 4,228 or 12.4 per cent were from Pakistan and 3,687 or 10·8 per cent were from Bangladesh.
This is the third significant study published since October bearing scientific evidence of how toxic air impacts human health. In October, the Health Effect Institute and Institute for Health Metrics had established the link between air pollution and infant mortality. In December, the results of the study under India State-Level Disease Burden Initiative, too, had attributed polluted air with human deaths in India.
Who are the most affected
Pregnancy loss associated with air pollution was more common in the northern plains region in India and Pakistan. This was probably due to their lower development and increased susceptibility of rural mothers to pregnancy loss.
(Spatial distribution of total burden of pregnancy loss and pregnancy loss attributable to PM2.5, 2000–2016: (A) Annual mean number of pregnancy losses (B) Mean incidence of pregnancy loss (C) Annual mean pregnancy loss attributable to PM2.5 (D) Mean fraction of pregnancy loss attributable to PM2.5. For parts C and D, the burden attributable to PM2.5 was quantified under a theoretical minimum risk exposure level of 40 μg/m³, the environmental standard for the annual PM2.5 concentration in India.)
In recent years, the total burden of pregnancy loss was predominantly borne by rural women younger than 30 years. But the burden attributable to PM2.5 also affected women above 30 in rural areas because of their high susceptibility to the adverse effects of the particulate matter.
This may hint at an association with household air pollution but the study does not account for indoor pollution, said the authors noting limitations of their study. It also does not distinguish between natural pregnancy loss and abortions.
First of its kind
Poor air quality is a major contributor to the global burden of pregnancy loss, show at least 13 studies across the United Kingdom, United States, China, Mongolia, and African countries. For example, in 2019, too, Tao had established the link between poor air quality on pregnancies lost in 33 African nations.
This is the first such estimate for South Asia, the authors claim.
According to Tao:
South Asia has the highest burden of pregnancy loss globally and is one of the most PM2.5-polluted regions in the world. Our findings suggest that poor air quality could be responsible for a considerable burden of pregnancy loss in the region, providing further justification for urgent action to tackle dangerous levels of pollution.
The findings of the study support public health interventions for reducing ambient particulate matter to improve maternal health in the South Asia.
Poor air quality is likely to increase the burden of pregnancy loss in low-income and middle-income countries compared with high-income countries.
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