Prenatal Exposure to Air Pollution Can Impact Heart Health During Infancy

A new study from Icahn School of Medicine at Mount Sinai is shedding new light on the impact of prenatal exposure to air pollution on heart health during infancy.

Results of the study indicated prenatal exposure to fine particulate matter (PM 2.5) could play a role in disrupting vagal tone during infancy, regardless of sex.

In an effort to evaluate potential associations between exposure to PM 2.5 and heart rate variability as an indication of cardiac autonomic control during infancy, investigators designed a birth cohort study of 237 maternal-infant pairs. All pairs in the study were recruited from prenatal clinics in the Boston area between March 2011 and August 2012.

For inclusion in the study, women had to be 18 or older, English- or Spanish-speaking, and pregnant with only one child. PM 2.5 exposure for participants was estimated using a model that accounts for population density, elevation, traffic density, land use type, area source emissions, and other variables.

At 6 months of age, investigators evaluated parasympathetic feverous system (PNS) activity using continuous electrocardiogram monitoring. Investigators noted the use of multivariable linear regression to examine associations between average PM 2.5 exposure during pregnancy and in relation to PNS withdrawal and activation, which was catalogued by changes in respiration-corrected respiratory sinus arrhythmia (RSAc).

Results of the adjusted analyses revealed a 1-unit increase in PM 2.5 was associated with a 3.53% decrease in baseline RSAc (95% CI: -6.96, 0.02). When evaluating change between episodes, investigators observed for every 1-unit increase in PM 2.5 exposure, the average reduction in RSAc during the first stress sequence was decreased by 0.74 units (95% CI: −0:12, 1.60), and the average decrease in RSAc during the second stress sequence was reduced by 0.61 units (95% CI: −0:43, 1.66)—indicating a possible inhibitory impact of PM 2.5 on PNS with withdrawal during stress.

Additionally, no significant associations were observed in analyses examining PM 2.5 and sex. Based on the results of their study, investigators suggested results of their study, in combination with previous research, highlight the need for a greater focus on the impact of air pollution on health.

“These findings, in combination with increasing worldwide exposure to PM 2.5, emphasize the importance of examining early life exposure to PM 2.5 in relation to autonomic outcomes,” investigators wrote. “However, until these preliminary findings are replicated by future studies, it is critical they be interpreted with caution.”

This study, titled “Prenatal Exposure to PM2:5 and Cardiac Vagal Tone during Infancy: Findings from a Multiethnic Birth Cohort,” was published in Environmental Health Perspectives.