Ambient Air Pollution, Chronic Stress, and Racial/Ethnic Disparities in Poor Birth Outcomes

Racial and ethnic disparities in birth outcomes in the United States are well documented, but have not yet been fully explained. Some recent studies have posited a link between exposure to chronic stress and risk of poor birth outcomes such as low birth weight (LBW) and pre-term birth (PTB). Another line of research conducted by environmental epidemiologists has linked poor birth outcomes with exposure to ambient air pollution. MPRC faculty associates Edmund Shenassa, Robin Puett, Sandra Hofferth, and Klaus Hubacek have been awarded an MPRC seed grant to begin a new study that examines the extent to which the elevated risk of poor birth outcomes observed among some minority populations is due to exacerbating effect of simultaneous exposure to both chronic stress and environmental pollutants.

Exposure to ambient air pollutants is more prevalent among low income families, who often reside close to areas of high traffic or industrial production. These areas also have high levels of social deprivations ranging from crowding and high unemployment to high crime and general lack of amenities. Such chronically stressful conditions can increase the body’s physiological wear and tear, as measured by allostatic load. Allostatic load (AL) refers to the cumulative biological burden exacted by ongoing dysregulation of the stress response due to chronic stress exposure. Previous studies have linked higher allostatic load with increased risk of aging-related health outcomes, including poor birth outcomes.

The research team will use data from birth certificates, the Maryland Pregnancy Risk Assessment Monitoring System (PRAMS), the Census, and the Environmental Protection Agency (EPA) to examine differences in air pollution levels across Maryland and estimate the association between ambient air pollution exposures with risk of poor pregnancy outcomes. They will then estimate racial/ethnic disparities in neonatal mortality, low birth weight, and pre-term birth and determine the extent to which these disparities are explained by disparities in ambient air pollution. In the second stage of the project, they will analyze laboratory data available from the National Center for Health Statistics to assess the physiologic burden of chronic stress and examine the interaction of chronic stress and exposure to environmental pollutants on the risk of neonatal mortality, low birth weight, and pre-term birth.

This project will be the first population-based study of the possible interactions between chronic stress, exposure to environmental pollutants, and poor birth outcomes.