A toxic cauldron

Chronic exposure to air pollution during pregnancy adversely affects the health of an expecting mother and the development of her baby, warns Dr Shashikala Hande

Every year, the onset of winter is automatically associated with poor air, respiratory and visibility problems. Residents and hospitals have started reporting a spike in respiratory illnesses, with many, especially children, complaining of breathlessness and other respiratory issues. It is important to understand that air pollution comes in many forms. Typically, polluted air comprises of ozone, particulate matter, nitrogen dioxide, sulphur dioxide, vehicle exhaust, building emissions, second-hand smoke, dust, and chemicals.

This toxic particulate matter irritates the lungs, eyes, and throat, making it difficult to breathe. While larger particles can be coughed or sneezed out of the body, smaller particles tend to get trapped in the lungs and enter the bloodstream.

Effects on pregnancy

There is enough evidence now to say that air pollution impacts pregnancy. A pregnant woman’s exposure to every 10-μg/m3 increase in PM 2.5 could result in a four-gram decline in the baby’s birth-weight, according to a 2018 study conducted in Chennai and its surrounding districts involving 1,285 pregnant women. PM 2.5 are fine particulate matter found in the air with a diameter of 2.5 micrometres or less and are known to pose the greatest risk to human beings. On an average, Delhi’s PM 2.5 measures between 100 and 180 10-μg/m3, over 10 times the standards set by the World Health Organisation (WHO). The median estimate in birth weight is a 72-gram increase, which means that you can expect somewhere around 70 to 80-gram increase in the newborns birth weight if they (pregnant women) lived in a cleaner area.

Associated risks

The foetus receives oxygen from the mother and breathing polluted air, therefore, affects the foetus. Exposure to outdoor air pollution before conception or during the early months of pregnancy can result in premature birth or birth defects of the brain and spine. Further, it can cause the baby to have a low birth weight and can increase the baby’s risk of contracting illnesses.

Miscarriages: Exposure to ammonium sulfate during pregnancy can increase the risk of birth defects and stillbirths. Sulfate is mainly produced from coal burning, while ammonium is derived from ammonia, which is produced from agricultural, automobile, and animal emissions.

Low birth weight: A pregnancy results in 2.5 to 3 kg for babies at 38–40 weeks ideally. Babies under 2.5 kg are considered low birth weight. Air pollution exposure results in low birth weight babies. However, it’s still unknown which trimester is most vulnerable to the effects of air pollution. Exposure to ozone during pregnancy can cause your baby to be born with low birth weight. Ozone is a gas that comes from car exhaust, gasoline and fumes from factories and chemicals.

Preterm birth: Children born prematurely have a significant risk of adverse outcome long term. According to a study by the Stockholm Environment Institute (SEI) at the University of York, nearly three million babies are born prematurely each year because of air pollution. That means 18 percent of all annual preterm births have been linked to exposure to particulate matter pollution.

Asthma: Asthma is a recurrent wheezy condition which requires constant medical attention. Air pollution exacerbates asthma.

In pregnant women, this can be dangerous because asthma can cause preeclampsia, a condition that causes elevated blood pressure and decreased function of the liver and kidneys. Untreated asthma can cause your baby to suffer from lack of oxygen, leading to poor growth, premature birth, and low birth weight.

Research has also found that exposure to air pollution can increase your baby’s chances of developing asthma later in life.

(The author is a consultant
obstetrician & gynaecologist.)