Air pollution's momentary contact may trigger an inflammatory response within the placenta, according to a recent lab study.
In a groundbreaking study conducted by a Swedish-Austrian research team and reported in 2025, the effects of fine particulate matter (Feinstaub) on the placenta were investigated. The research, published in the Journal of Environmental Sciences, used "ex vivo dual placental perfusion" to study the impacts of these pollutants.
The study focused on "fine" particulate matter, or PM2.5, which includes particles smaller than 2.5 micrometers. These particles, drawn from a previous sampling of air pollution in Malmö, Sweden, in spring 2017, were introduced into the system to observe their effects on the placenta.
After an hour of exposure, the placentas started making more human chorionic gonadotropin (hCG). This hormone, commonly associated with pregnancy, may have implications for the risk of preeclampsia, as high levels of hCG in the second trimester have been tied to a higher risk of this condition, according to studies.
Exposure of placentas to these pollutants for 30 minutes caused distinct changes in collagen, making it looser and disrupted. The Hofbauer cells of the exposed placentas also had a visible activated appearance and shifted into an inflammatory state. In a healthy placenta, the Hofbauer cells are typically biased toward an anti-inflammatory state.
The results hint that subduing the inflammation driven by the Hofbauer cells may help ward off one factor contributing to preeclampsia in polluted areas. However, Dr. Grigg, a professor of pediatric respiratory and environmental medicine at Queen Mary University of London, cautioned that the new results don't necessarily point to precautions that individual pregnant people should take.
A more effective intervention, according to Dr. Grigg, would be to reduce particulate matter in the air. The research will also run in the journal's February 2026 print issue.
The study collected full-term placentas from 13 healthy volunteers. Dr. Stefan Hansson, a study co-author, is a professor of obstetrics and gynecology and a senior consultant in obstetrics at Lund University in Sweden.
Air pollution may alter the structure of the placenta and push it into an inflammatory state. This research provides valuable insights into the potential risks associated with air pollution during pregnancy and underscores the need for continued research in this area.
