Infants exposed in the womb to higher levels of PM2.5 were significantly more likely to be born underweight or preterm. These microscopic particles primarily come from burning fossil fuels, biomass, vehicle emissions, construction dust, and even household cooking with solid fuels like wood or dung cakes.
Published Jul 09, 2025 | 7:00 AM ⚊ Updated Jul 09, 2025 | 7:00 AM
Air pollution (Creative Commons)
Synopsis: Air pollution and rising climate extremes are significantly increasing the risk of premature and low-weight births across India, according to a nationwide study using satellite data and health survey records. The research links high exposure to PM2.5 particles – especially in North India – to a steep rise in adverse birth outcomes, with young, undernourished and poorly educated mothers most affected.
In the first national-scale study of its kind, researchers have provided definitive evidence that the air Indian mothers breathe while pregnant could be silently endangering their unborn children.
The study, published in PLOS Global Public Health, used data from the National Family Health Survey (NFHS-5) and advanced satellite-based modelling to track how exposure to PM2.5 – tiny but deadly airborne particles – affects birth weight and the likelihood of premature delivery.
Infants exposed in the womb to higher levels of PM2.5 were significantly more likely to be born underweight or preterm.
Specifically, for every 10 micrograms per cubic metre (μg/m³) rise in PM2.5 during pregnancy, the odds of a baby being born with low birth weight rose by 5 percent, and the odds of being born preterm rose by 12 percent.
PM2.5 refers to particulate matter that is less than 2.5 microns in diameter – nearly 30 times smaller than the width of a human hair.
These microscopic particles primarily come from burning fossil fuels, biomass, vehicle emissions, construction dust, and even household cooking with solid fuels like wood or dung cakes.
Because they are so small, PM2.5 particles are uniquely capable of bypassing the natural defences that the human body has against external matter and can be inhaled deeply into the lungs, enter the bloodstream, and even cross the placental barrier – reaching the foetus.
Once inside the body, they trigger a cascade of harmful reactions.
This includes inflammation, disrupting hormone levels, interference with oxygen transport, and even cause oxidative stress – conditions that hinder foetal development and can lead to premature birth or low birth weight.
The paper explains that the developing foetus is extremely sensitive to environmental changes, especially in the third trimester when it grows the fastest.
During this time, exposure to pollutants like PM2.5 can hamper the supply of nutrients and oxygen, damage DNA, and alter hormone levels, which are all vital for healthy foetal development.
The data showed that once PM2.5 exposure crosses the threshold of 40 μg/m³ (which is also India’s national standard), the risk of adverse birth outcomes rises steeply.
The study analysed over 2.3 lakh births across 36 states and union territories in India between 2019 and 2021.
Among the children born in this period, 13 percent were born preterm (before 37 weeks of pregnancy), and 17 percent were born with low birth weight (less than 2,500 grams).
Low birth weight and preterm birth are major predictors of infant mortality and lifelong health complications, such as malnutrition, developmental delays, and chronic illnesses.
The study shows a clear geographic pattern. North Indian states, including Delhi, Uttar Pradesh, Bihar, Punjab, and Haryana, are the worst affected. These areas not only have high concentrations of PM2.5 but also record the highest rates of adverse birth outcomes.
Districts like Delhi and parts of Punjab and Uttar Pradesh showed what researchers call “high-high clusters” – zones where both pollution and negative birth outcomes are alarmingly high.
In fact, over 100 districts had a statistically significant link between high in-utero PM2.5 exposure and low birth weight.
In contrast, the Northeastern states – except Nagaland – had much lower rates of preterm births and low birth weight, correlating with better air quality.
While air pollution was the primary focus, the study also looked at how climate factors – like temperature and rainfall – affect pregnancy outcomes.
Findings show that high temperatures can cause heat stress, dehydration, and cardiovascular strain in pregnant women, all of which can disrupt foetal development.
Similarly, excessive rainfall can increase the risk of infections, reduce healthcare access, and cause malnutrition, all of which can harm both mother and child.
It also found that women who cooked using solid fuels (wood, dung, or crop waste) were more likely to have babies with low birth weight. This is critical, given that more than 57 percent of households in the sample relied on solid fuels for cooking.
Certain demographic groups were more at risk. Teenage mothers had the highest chances of adverse outcomes. Underweight women were more likely to give birth to preterm or low-weight babies.
Mothers with little or no education, those living in poverty, and those delivering at home also showed worse outcomes.
According to the authors, the geostatistical analysis underscores the need for targeted interventions, particularly in Northern states. In addition, the National Clean Air Programme should be intensified, with stricter emission standards and enhanced air quality monitoring.
Climate adaptation strategies, such as developing heat action plans and improving water management, should be incorporated into public health planning to mitigate the effects of extreme temperatures and irregular rainfall.
Public health initiatives should be implemented to raise awareness of the risks of air pollution and climate change, particularly among pregnant women.
(Edited by Dese Gowda)
