How air pollution impacts the health of pregnant women and foetuses

In September, a group of researchers studying the effects of air pollution on human health recommended to the Union Health Ministry that polluting cooking stoves, which are commonly used in Indian villages, be removed from the homes of pregnant women.

The group wants to reduce the exposure of pregnant women to air pollutants emitted from biomass-burning stoves to ensure that the children born to them are not low in weight.

This is perhaps the first time that the role of pollutants in adversely impacting pregnancy has been acknowledged for a policy intervention.

These recommendations were made by a steering committee formed by the Union Ministry of Health and Family Welfare last year to draft a report looking at the impact of air pollution on human health.

“India has a difficult air pollution system,” said Kirk Smith, professor Global Environmental Health, University of Berkeley, who is part of the steering committee formed by the health ministry. “About 30% of outdoor air pollution is a result of using chulhas.”

Health risk

Contrary to the popular belief that air pollution is responsible for triggering and worsening respiratory ailments, a growing body of evidence has linked air pollution to heart disease, strokes and cancer.

Thus, the risk that air pollution poses to the health of unborn children is another challenge for policy makers already struggling to improve child health.

Sutapa Neogi from the Public Health Foundation of India conducted a study on household air pollution that was published in 2015 where she found a strong association between household air pollution and neonatal mortality and still births.

The steering committee had looked at several studies, including Neogi’s, before making its recommendations to the government.

“We don’t know the mechanism,” said Neogi. “The assumption is that prolonged exposure to air pollution affects the oxygen supply to the foetus.”

In her study, Neogi analysed the health indicators of nine large states in India using data from the Annual Health Survey – a population-based survey conducted by the Central government.

Child specialists say that the foetus receives oxygen from the mother, and if she is breathing polluted air, it is bound to impact the development of the unborn child.

This, in turn, has a cascading effect on the child’s future development. For instance, children whose weight is low at birth are at a higher risk of contracting illnesses, say doctors. In fact, babies with low birth weight also tend to be malnourished as they grow older. Some studies have found that a low birth weight baby is more likely to develop diabetes, heart conditions and blood pressure later in life.

Low vitamin D levels

Studies have also found that high air pollution levels can have an impact on the body’s absorption of vitamin D, which promotes calcium absorption, is vital for bone growth and also plays an important role in boosting immunity.

In 2002, doctors from St Stephens Hospital in Delhi conducted a study into the impact of air pollution on vitamin D levels in children.

“We oversimplified it but more the pollution, the lesser is the absorption of ultraviolet radiation in children which is major source of vitamin D,” said Dr Jacob M Puliyel, a paediatrician, one of the authors of the study.

Puliyel and his colleagues looked at the vitamin D status of children living in Mori Gate in central Delhi and Gurugram in neighbouring Haryana. Mori Gate has high air pollution levels as compared with Gurugram. The study found that children living in Mori Gate had low levels of vitamin D as compared with those living in Gurugram. They concluded that children living in polluted areas should be provided with vitamin D supplements to avert their risk of developing rickets, a skeletal disorder that is caused by the lack of that crucial vitamin in the body.

In 2012, another group of researchers from France linked air pollution with low vitamin D levels in newborns. During their study, they tested cord blood and found low levels of vitamin D among mothers who were exposed to high pollution levels. The group concluded that gestational exposure to ambient urban air pollution, especially during late pregnancy, may contribute to lower vitamin D levels in babies.

Puliyel said that India needed to conduct a similar study especially because there was an unexplained rise in the number of children with low calcium levels.

“I am definitely seeing too many children coming with convulsions which are a result of low calcium levels,” said Puliyel.

Doctors, governments clueless

Public health experts said that despite the growing body of evidence linking air pollution with pregnancy outcomes, little has been done to inform the community at large.

“Air pollution has not been a part of the medical curriculum,” said Smith, who conducts research on environmental and health issues caused by pollution in developing countries, including India.

The reasoning here is that if doctors are not educated on the problems of air pollution they will be unable to pass the message to their patients.

“A doctor in the village has to tell a pregnant woman that cooking on the traditional stove can damage her child,” said a senior doctor working with a medical college in Maharashtra. “We have observed that even if women are provided with non-polluting stoves, they will still use the traditional stove to cook some items.”

Associating low birth weight with air pollution is a challenge as it is caused by multiple factors. For instance, small babies are also routinely born to mothers with poor nutritional status, and to young mothers.

“There are enough reasons to act,” said K Srinath Reddy, president of Public Health Foundation of India and co-chair of the steering committee set up by the health ministry.

Though officials at the health ministry said that very little has been done to act on the recommendations, Reddy and his colleagues are optimistic. “India is the only country where the health ministry is acting,” said Smith. “Usually the environment ministries take a lead in most countries.”

However, public health experts say that India has a long history of forming committees, but does not always effectively implement their recommendations.

India’s commitment (or lack of it) to the problem of air pollution is evident from an incident early this year, when a funds crunch at the Indian Council of Medical Research led to the derailment of a multi-level study on air pollution and its impact on human health in the country.