When a pregnant woman breathes in polluted air, sooty particles may reach her baby’s placenta, new research suggests.
The study, presented on Sunday at the European Respiratory Society International Congress, adds to existing evidence about the dangers of air pollution for unborn babies
Previous research indicated links between expectant mothers being exposed to air pollution during pregnancy and premature birth, low birth weight, infant mortality and childhood respiratory problems.
“We’ve known for a while that air pollution affects foetal development and can continue to affect babies after birth and throughout their lives,” said Dr Lisa Miyashita, a post-doctoral research scientist.
“We were interested to see if these effects could be due to pollution particles moving from the mother’s lungs to the placenta. Until now, there has been very little evidence that inhaled particles get into the blood from the lung.”
The researchers worked with five pregnant women who were living in London and due to have planned caesarean section deliveries at the Royal London Hospital. All five were non-smokers with uncomplicated pregnancies and they each gave birth to a healthy baby. The women gave permission for researchers to study their placentas after delivery.
The study was interested in a particular group of cells known as placental macrophages. Macrophages exist in many different parts in the body as part of its immune system. They work by engulfing harmful particles such as bacteria and pollution particles and, in the placenta, they help to protect the foetus.
Using a high-powered microscope to examine 3,500 placental macrophage cells from the five women’s placentas, the team found 60 cells that, between them, contained 72 small black areas believed to be carbon particles. On average, each placenta contained around five square micrometres of this black substance.
“On average, each placenta contained around five square micrometres of this black substance”
The researchers went on to study the placental macrophages from two placentas in greater detail using an electron microscope, and again found material they believe was made up of tiny carbon particles.
In previous research, the team used the same techniques to identify and measure these sooty particles in people’s airways. By studying macrophages in other organs, said researcher Dr Norrice Liu, they were looking for direct evidence that “inhaled particles” could move from the lungs to other parts of the body.
“We were not sure if we were going to find any particles and if we did find them, we were only expecting to find a small number of placental macrophages that contain these sooty particles,” said Dr Liu. “Our results provide the first evidence that inhaled pollution particles can move from the lungs into the circulation and then to the placenta.
“We do not know whether the particles we found could also move across into the foetus, but our evidence suggests that this is indeed possible. We also know that the particles do not need to get into the baby’s body to have an adverse effect, because if they have an effect on the placenta, this will have a direct impact on the foetus.”
Professor Mina Gaga, president of the European Respiratory Society, who was not involved in the study, said: “This new research suggests a possible mechanism of how babies are affected by pollution while being theoretically protected in the womb. This should raise awareness amongst clinicians and the public regarding the harmful effects of air pollution in pregnant women.
“We need stricter policies for cleaner air to reduce the impact of pollution on health worldwide because we are already seeing a new population of young adults with health issues.”
How to find out the current level of air pollution in your area:
You can find out the current level of air pollution in your region by heading to the Defra website, where you can click coloured area on the map to view information. The results are based on the maximum air quality index measured across all stations in each region.
The colour code highlights pollutions levels from “low” up to “very high”. Click here to find out what the pollution level is where you live. Or to get up-to-date alerts, follow the daily forecast tweets on Twitter.
Defra advises people to use the Air Quality Index to determine whether they or their children are likely to be at risk from air pollution and to consult their doctor for advice if necessary.