A study by researchers at AIIMS Delhi has mapped the biological pathway through which urban air pollution harms unborn babies, showing that particulate matter can breach the placental barrier, trigger oxidative stress and inflammation, and disrupt foetal development in ways that may continue into late childhood.
The ICMR funded research, published in EMBO Molecular Medicine, traced what it described as the step by step molecular process by which PM2.5 and PM10 exposure during pregnancy suppresses IGFBP3, a protein critical to placental balance and embryo growth. The study linked this disruption to placental dysfunction, preterm birth, low birth weight and preeclampsia.
How Pollutants Disrupt Foetal Growth
According to the study, exposure to urban particulate matter activates inflammatory pathways that inhibit IGFBP3 expression, weakening key processes that support the placenta and the developing embryo.The researchers set out to examine the pathways through which pollutants cause distress to the placenta and the foetus and to show the entire pathway rather than isolated fragments of it.
The study said this reduction in IGFBP3 impairs critical placental processes and alters developmental trajectories. Researchers reported that particulate matter can breach the placental barrier and set off oxidative stress and inflammation, causing molecular changes that undermine the placenta’s ability to function normally through pregnancy.
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The work drew on data from 994 deliveries across two cities, high pollution Delhi and low pollution Deoghar in Jharkhand, and was supplemented by parallel experiments on rodents.
Findings From Delhi and Animal Experiments
Among women in Delhi, PM2.5 exposure emerged as a clear risk factor for low birth weight. The study also found that rates of preeclampsia, a dangerous rise in blood pressure during pregnancy, climbed as pollution levels increased.
In rodents, researchers found that particulate matter weakened the placenta’s ability to anchor into the uterine wall, form its nutrient exchange layer and grow blood vessels. It also pushed cells into severe stress and altered epigenetic switches, permanently changing which genes turn on or off.
The paper further reported that pregnant rats exposed to Delhi’s pollution levels had litters that were up to 25 per cent smaller, placentas that were reduced in size, and newborns that weighed 34 per cent less at full term. These findings were used to support the molecular link identified in the human data.
Effects Seen Beyond Birth
The study said the effects of pollution exposure in the womb were not limited to pregnancy outcomes or birth size. The offspring in the rodent experiments also showed neurological deficits, including poor motor coordination, higher anxiety and altered stress responses.
Researchers said these findings suggest that the impact of urban air pollution during pregnancy can stretch well beyond birth and into later stages of childhood development. By linking placental damage with longer term neurological consequences, the study places fresh emphasis on air pollution as a public health risk not only for pregnant women but for children before they are even born.
The research adds to a growing body of evidence that polluted air is not only an environmental issue but a direct biological threat to maternal and foetal health. In identifying a specific protein pathway and documenting its consequences, the study offers one of the clearest explanations yet of how exposure during pregnancy may translate into lasting developmental harm.
