Asthma Risk Increased With Prenatal Exposure to Air Pollution

Prenatal exposure to ambient fine particulate matter (PM_2.5) and stress are linked to increased likelihood of asthma, specifically in boys by the age of 6 years, according to research presented at the American Thoracic Society (ATS) 2017 International Conference, held May 19-24 in Washington, DC.¹

Alison Lee, MD, assistant professor at the Icahn School of Medicine at Mount Sinai in New York City, and colleagues examined connections between prenatal PM_2.5 exposure and asthma in early childhood, taking into account timing of exposure and whether the effects were modified by prenatal stress and child sex.

The study included 736 mothers and their full-term infants, classified as ≥37 weeks’ gestation. The researchers followed mothers and infants until the infants were 6 years old to ascertain physician-diagnosed asthma.

Daily PM_2.5 exposure in mothers was measured using a satellite-based spatiotemporal resolved model, and prenatal stress was measured using a negative life events score. Bayesian-distributed lag interaction models were used for the effects of weekly averaged PM_2.5 exposure on child asthma while accounting for child sex and prenatal stress.

The investigators report associations between higher PM_2.5 exposure at 13 to 20 weeks’ gestation and increased chances of asthma among boys. The odds increased among boys born to mothers reporting high prenatal stress (odds ratio, 1.20; 95% CI, 1.10-1.34; per interquartile range [IQR] increase in PM_2.5), followed by boys born to mothers reporting low prenatal stress (odds ratio, 1.06; 95% CI, 0.94-1.20). The researchers report no significant associations among girls regardless of maternal prenatal stress level.

“It isn’t clear at this point why boys are more impacted, but scientists think it may be related to the fact that boys’ lungs mature at a slower rate compared to girls. This, coupled with male fetuses’ increased risk for specific types of injury, such as oxidative stress, may increase the risk of respiratory disease when co-exposure to ambient air pollution and stress occurs during the prenatal period,” said Dr Lee in a press release.²

References

1. Lee A, Chiu Y, Hsu H, et al. Prenatal exposure to fine particulate matter is associated with early childhood asthma: influence of exposure timing and effect modification by prenatal stress and child sex. Presented at: American Thoracic Society (ATS) 2017 International Conference; Washington DC; May 19-24. Abstract 8941.
2. High levels of prenatal air pollution exposure and stress increase childhood asthma risk. New York, NY: American Thoracic Society. http://www.thoracic.org/about/newsroom/press-releases/conference/2017/lee-air-pollution-and-asthma.php  Published May 22, 2017. Accessed May 22, 2017.