Prenatal air pollution exposure linked to decreased heart rate response to stress

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 new research by Mount Sinai Hospital in New York. The study was published in the journal Environmental Health Perspectives.

Variability in how the heart rate responds to stressful experiences is essential for maintaining optimal functioning of the cardiovascular, respiratory, and digestive systems, and is central to emotional wellbeing and resilience to stress over one's lifetime, the researchers said.

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.

For the study, 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 U.S. 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. The 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, according to Rosalind Wright, MD, MPH, senior author and Dean for Translational Biomedical Research at Mount Sinai School of Medicine.

"A critical step in identifying children at risk for costly chronic disorders is identifying exposures that lead to early vulnerability,” said 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, said Whitney Cowell, PhD, the study’s first author and postdoctoral fellow in Environmental Medicine and Public Health.

“Specifically,” said Cowell. “these findings support individual-level and policy-level action to reduce exposure to particulate air pollution exposure during pregnancy.”