Exposure to air pollution is associated with an increased risk of birth defects, a new study finds, adding to a growing line of research linking environmental pollutants with serious health consequences in developing fetuses.
The health effects of air pollution are a major concern for urban populations all over the world. Children, the elderly, and people with impaired respiratory systems (such as asthmatics) tend to be especially sensitive to the impact of exposure to pollutants such as ozone, nitrogen dioxide, sulphur dioxide, and particulate matter.
Recently, however, researchers have discovered that many of these pollutants possess the ability to cross the placental barrier and get into the blood supply of developing fetuses, causing potentially devastating effects. Studies have shown, for instance, that mothers exposed to high levels of air pollution — especially fine particulate matter — are significantly more likely to have a child with autism, while other research has linked air pollution with a heightened risk of childhood Attention Deficit Hyperactivity Disorder, schizophrenia, and inflammation and neurodegeneration in the brain.
In this latest study, researchers from Tel Aviv University add new evidence on the dangers of air pollution, finding a significantly increased risk of congenital malformations in the offspring of mothers exposed to high levels of certain pollutants.
The nationwide study, the results of which are published in the journal Environmental Research, is the first to assess the association between different modes of conception-assisted reproductive technology (ART) versus spontaneous conception (SC) – and the risks of exposure to air pollution to each.
“Our results suggest that exposure to higher levels of air pollution during pregnancy is associated with various adverse pregnancy outcomes,” said Prof. Lerner-Geva. “While our study mainly followed SC infants, we also had the opportunity to assess a small sample of pregnancies that were conceived through ART, and observed a higher impact of air pollution – particularly with regard to ozone exposure. This is clearly a uniquely susceptible population that should be further explored.”
Analysis links pollution to defects
For the study, funded by the Environmental Health Fund (EHF), the research team analyzed data on 216,730 infants born in Israel between 1997 and 2004. Air pollution data, including levels of sulfur dioxide (SO2), particulate matter (PM10), nitrogen oxides (NOx), and ozone (O3), were obtained from air monitoring stations for the study period. Using a geographic information system, exposure to air pollution during both the first trimester and the entire pregnancy was assessed for each woman according to her place of residence.
The researchers found that exposure to PM10 and NOX pollutants throughout full-term pregnancies were associated with an increased risk of congenital malformations, with specific defects evident in the circulatory system (from PM10 and NOX exposure) and genital organs (from NOX exposure). They also discovered that exposure to SO2 and O3 in ART pregnancies were associated, although not significantly, with a higher risk of congenital defects.
“Considering the worldwide decline in fertility, and the increasing number of children born through ART treatments, our findings about their increased risk of congenital malformations are very relevant,” said Prof. Lerner-Geva. “It is essential we continue to evaluate this unique population.”
According to Prof. Lerner-Geva, a national ART registry has been established in Israel to provide important data on all ART cycles. This database will serve as a basis for a future larger study to identify susceptible subpopulations at higher risk of adverse pregnancy outcomes. Prof. Lerner-Geva is currently engaged in a more detailed assessment of environmental exposure during pregnancy.