In India, Air Pollution Can Increase The Risk Of Preterm Birth: Study

India is the third most polluted country in the world, largely due to its extraordinarily high levels of air pollution. While seven out of 10 Indians are exposed to noxious air, pregnant women and their unborn children are among the most impacted. According to a recent study, prenatal exposure to air pollution could increase the risk of a preterm birth by at least 12% and a 5% higher risk of low birth weight — especially in North India.

“Medical studies found that the fetus grows rapidly in the third trimester of pregnancy. That period is more sensitive, and exposure to PM2.5 can hemorrhage fetal growth. Nevertheless, the level of thyroid hormone might be affected by the toxicity of PM2.5, which is a responsible factor for less fetal weight,” the researchers explained in the study.

“Previous studies have found that the concentration of ambient fine particulate matter (also known as PM2.5) is highest in the states of the upper-Gangetic plains such as Delhi, Punjab, Haryana, Uttar Pradesh, and Bihar, as observed in the present study. A recent Lancet study suggests that the average PM2.5 concentrations in Delhi were 13.8 times higher than those in Kerala,” the researchers wrote. The first trimester is the most risky period as PM2.5 exposure during this stage, which is above 21.36 μg m3, is linked to higher odds of adverse birth outcomes.

“A large proportion of households in the Northern parts of India use solid fuels compared to other regions. It is well documented that the residential sector is a significant contributor to the total PM2.5 emissions, along with the industry, energy, and agriculture sectors. Among industrial, residential, and energy sources, the contribution of energy sources to total emissions is the maximum, while residential sources contribute the maximum to PM2.5 emissions during winter and post-monsoon,” they added. “However, at the urban or city level, where most households are already using cleaner fuel, reducing vehicular emissions (both exhaust and non-exhaust) emerges as a crucial strategy for reducing PM2.5 levels. It was prominently observed during the coronavirus pandemic (Covid-19) lockdown in Indian cities when traffic reduction substantially minimized urban areas’ exposure to air pollutants.”

To date, several studies have shown the deleterious health impacts of unborn children being exposed to large amounts of PM2.5. In the last seven years, researchers have linked this form of air pollution to fetal malformation, miscarriages, and stillbirths.

Air pollution is in the top five risk factors for early deaths, in both men and women, making it one of the most omnipresent “silent killers.” Scientists estimate that in 2019 itself, particulate matter pollution was linked to over 4.14 million deaths globally. PM2.5 is the most harmful air pollutant, and its major sources are the burning of fossil fuels, such as coal, oil, and gas. Due to the extremely tiny size of PM2.5, which is less than 2.5 microns, it worsens the risk of getting heart disease, lung cancer, respiratory diseases, and stroke.

The study was published in PLoS Global Public Health on July 2, 2025.