Air pollution could be responsible for preterm births around the world, a new study has found. When a child is born before 37 weeks of gestation, the birth is classified as preterm. A prematurely born child has an increased risk of dying or developing long-term physical and neurological disabilities.

“This study highlights that air pollution may not just harm people who are breathing the air directly, it may also seriously affect a baby in its mother’s womb,” said Chris Malley, lead author of the study and researcher at the Stockholm Environment Institute at the University of York in the United Kingdom. There are several factors such as mother’s age and illness during gestation, which can contribute to a preterm birth. Researchers in the study has established that air pollution is also a factor triggering premature births worldwide.

The researchers said that in 2010, about 18% of all preterm births recorded globally were associated with outdoor exposure to fine particulate matter smaller that 2.5 microns or PM2.5. This air pollutant is known to damage human health as it has the tendency to penetrate deep inside the lungs which can lead to respiratory distress. Major sources of PM2.5 are diesel vehicles, biomass fuel and agricultural waste-burning.

In 2010, an estimated 14.9 million births were preterm. Four or five per cent of all births in European countries were preterm but the number rose to 18% in some African and South Asian countries. India alone accounted for about one million preterm births and and China for about another 5,00,000.

The study showed that preterm births and resulting infant mortality can be reduced by cutting down PM 2.5 emission and pregnant women’s exposure to pollutants should be reduced. In November, reported the relation between air pollution and its impact on the health of pregnant women and foetuses.