A quarter of stillbirths is attributable to PM 2.5 exposure during gestation; Highest average PM2.5-related stillbirths in India
A new study has found that countries with higher rates of stillborn babies had higher amounts of fine particulate air pollution. India leads the list with the highest average number of stillbirths — 217,000 out of 25 million births each year.
India was followed by Pakistan (110,000), Nigeria (93,000), China (64,000) and Bangladesh (49,000).
The highest fraction of stillbirths attributable to particulate matter (PM) 2.5 pollution were seen in Qatar (71.16 per cent); Saudi Arabia (68.38 per cent); Kuwait (66.08 per cent); Niger (65.68 per cent) and the United Arab Emirates (64.63 per cent), the study said.
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South Asia, sub-Saharan Africa, and the Arabian Desert were hotspots of PM 2.5-related stillbirths due to high exposure and baseline stillbirth rate, it further found.
The first global risk assessment on PM 2.5-related stillbirths, published in the journal Nature Communications on November 29, 2022, found that at least a quarter of stillbirths is attributable to PM 2.5 exposure during gestation.
The study covered 137 countries in Asia, Africa and Latin America, where 98 per cent of stillbirths occurred.
Among all subtypes of pregnancy loss (early stillbirth, miscarriage, or pregnancy loss), stillbirth was most strongly associated with PM 2.5 exposure.
A 10-microgram per cubic metre (μg/m3) increase in PM 2.5 is associated with an 11 per cent increase in the risk of stillbirth, and the association is significantly enhanced by maternal age.
“Based on age-specific nonlinear PM 2.5–stillbirth curves”, the researchers led by Tao Xue from Peking University Health Science Centre evaluated the PM 2.5-related stillbirths in 137 countries.
In 2015, of 2.09 million stillbirths, 0.83 million or 39.7 per cent can be attributed to PM 2.5 exposure ‘exceeding the reference level of 10 μg/m3’, said the study.
The researchers analysed 46,319 cases of gestation linked to 13,870 mothers from 1998 to 2016.
The results found that the exposure level among women at peak reproductive age (20–34 years) was higher than that in the adolescent pregnancy (<20 years old) and geriatric pregnancy (>34 years old) groups.
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“Across locations where PM 2.5 concentration was from 10 to 100 μg/m3, the proportion of pregnant women 20–29 years old was positively correlated with exposure level,” the study said.
All the mothers in the study were exposed to PM 2.5 levels above the WHO’s guideline level of 5 micrograms per cubic metre (μg/m3).
Efforts to promote maternal health were unequal for different adverse outcomes and interventions relevant to stillbirths are inadequate.
A 2020 report by UNICEF called stillbirths a neglected tragedy, with one stillbirth occurring every 16 seconds. This comes to 2 million babies being stillborn every year.
Even though stillbirths are an increasingly critical global health problem, this loss of life has largely remained a neglected issue in many countries. Stillbirth was not included in the Millennium Development Goals and neither was it tracked by the Global Burden of Disease (GBD) study — both of which counted only live births.
A stillbirth is the death or loss of a baby before or during delivery. Both miscarriage and stillbirth describe pregnancy loss, but they differ according to when the loss occurs. A baby who dies after 28 weeks of pregnancy but before or during birth is classified as a stillbirth by World Health Organization.
In the United States, a miscarriage is usually defined as the loss of a baby before the 20th week of pregnancy and stillbirth is the loss of a baby at or after 20 weeks of pregnancy.
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In 2014, the World Health Assembly endorsed the Every Newborn Action Plan (ENAP), which includes a global target of 12 or fewer stillbirths per 1000 total births in every country by 2030.
One year after the ENAP was endorsed at the 67th World Health Assembly, ‘15 of 18 low-resource countries identified as having the highest newborn mortality rates took action to improve maternal and newborn care around the time of birth and to save lives’.
At least four countries — Ghana, India, Indonesia and Pakistan — finalised national newborn action plans. Six countries — Namibia, Philippines, Rwanda, Tanzania, Uganda and Zambia — improved their health programs to save the lives of women and newborns.
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