Air Pollution:

A Growing Concern for the Growing Fetus

Lay summary by Rachel Shaffer

Don’t hold your breath if you’re pregnant, but you may want to pay attention to levels of air pollution in your local area. A new study published in Environmental Research suggests that these exposures may result in an increased risk of facial birth defects.

Air pollution has been associated with numerous adverse health effects. Few studies, however, have examined the relationship between air pollution and the development of orofacial defects, such as cleft palate and cleft lip.

In this study, researchers set out to investigate the association between maternal exposure to air pollution during preconception (within 3 months of becoming pregnant) and early pregnancy, and the risk of orofacial defects in a retrospective cohort. They focused their study on common air pollutants: carbon monoxide (CO), nitrogen oxides (NOx), ozone (O3), particulate matter (PM2.5 and PM10), and sulfur dioxide (SO2).

Using average air pollutant levels in the delivery hospital region for the time periods of interest (preconception and early gestation), the researchers were able to estimate maternal exposure to the pollutants. Analysis of this exposure data with birth outcome data suggests that several pollutants are associated with increased risk of orofacial defects. In particular, exposure to CO, NOx, and PM2.5 during early gestation and exposure to CO and PM10 during preconception are associated with increased risk of cleft palate. Exposure to SO2 during preconception is associated with increased risk of cleft lip.

Not only does this study provide data to support the possible environmental origins of orofacial defects, but it also adds to a growing body of evidence linking specific windows of exposure with specific adverse outcomes. Risk estimates appeared to vary based on the timing of exposure during the early weeks of gestation, when palate formation occurs. Some risk estimates, however, were also elevated based on exposure prior to conception, suggesting a more chronic effect of pollution. Since it is challenging for individuals to avoid air pollution, society-wide efforts to ensure cleaner air are critical to minimize health risks to the next generation.

For further information

Read the Environmental Research original research article which this summary is based on Maternal ambient air pollution exposure preconception and during early gestation and offspring congenital orofacial defects (July 2015).

Visit the profile of the research ambassador, Rachel Shaffer, who wrote this summary.

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