A mother’s exposure to particulate air pollution during pregnancy is associated with reduced cardiac response to stress in six-month-old infants, according to an open-access study by researchers at Mount Sinai research published in Environmental Health Perspectives.

This study is the first to find that particulate air pollution exposure in utero can affect heart rate variability, which is a known risk factor for health issues.

Variability in how the heart rate responds to stressful experiences is essential for maintaining optimal functioning of the cardiovascular, respiratory, and digestive systems and also is central to emotional well-being and resilience to stress over one’s lifetime.

Decreased heart rate variability, as observed in this study, is a known risk factor for mental and physical health problems in later life. Air pollution’s negative effect on heart rate variability has previously been found to lead to medical and psychological conditions such as heart disease, asthma, allergies, and mood or behavioral disorders in studies of older children, adolescents, and adults.

Mount Sinai researchers studied 237 Boston-based mothers and their infants and used satellite data and air pollution monitors to determine the level of particulate air pollution the mothers were exposed to during pregnancy. The air pollution levels in this study were similar to levels experienced by the general US population.

By studying the babies’ heart rate and respiration at age six months, researchers found that the higher the level of the mother’s exposure to air pollution in pregnancy, the less variability in the infant’s heart rate in response to a stress challenge.

These findings, in combination with increasing worldwide exposure to particulate air pollution, highlight the importance of examining early-life exposure to air pollution in relation to negative medical, developmental, and psychological outcomes. A critical step in identifying children at risk for costly chronic disorders is identifying exposures that lead to early vulnerability.

—senior author Rosalind Wright

Identifying exposures that disrupt key processes such as heart rate response will lead to prevention strategies early in life when they can have the greatest impact. Specifically, these findings support individual-level and policy-level action to reduce exposure to particulate air pollution exposure during pregnancy.

—first author Whitney Cowell

Resources

• Whitney J. Cowell, Kelly J. Brunst, Ashley J. Malin, Brent A. Coull, Chris Gennings, Itai Kloog, Lianna Lipton, Robert O. Wright, Michelle Bosquet Enlow, and Rosalind J. Wright (2019) “Prenatal Exposure to PM_2.5 and Cardiac Vagal Tone during Infancy: Findings from a Multiethnic Birth Cohort” Environmental Health Perspectives Volume 127, Issue 10 doi: 10.1289/EHP4434