The study adds to existing evidence on the dangers of pollution for unborn babies and suggests that when pregnant women breathe polluted air, sooty particles are able to reach the placenta via the bloodstream. Previous research has indicated links between pregnant mothers’ exposure to air pollution and premature birth, low birth weight, infant mortality and childhood respiratory problems.
Dr Lisa Miyashita, who worked on the study at Queen Mary University of London, said, “Until now, there has been very little evidence that inhaled particles get into the blood from the lung. We were interested to see if these effects could be due to pollution particles moving from the mother’s lungs to the placenta.”
The researchers studied cells called placental macrophages, which are part of the body’s immune system and work by engulfing harmful particles, such as bacteria and pollution particles, and help to protect the fetus. A high-powered microscope was used to look for small black areas that researchers believe were carbon particles.
Out of a total of 3,500 placental macrophage cells, 60 contained 72 small black areas between them. Tiny carbon particles were also found on two placentas using an electron microscope.
“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 fetus, but evidence suggests this is possible,” said Norrice Liu, a clinical research fellow at the European Respiratory Society International Congress.
“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, it will directly impact the fetus.”