Using area-based exposures to evaluate the relationship between maternal stress and birth outcomes

Objective: Studies evaluating the effect of maternal stress on preterm birth (PTB) or low birth weight (LBW) and variations across neighborhood exposures have been inconclusive. The purpose of the study was to examine the relationships among neighborhood exposures, prenatal stress and birth outcomes, and to further explore the modifying effects of neighborhood contexts. Methods: We evaluated this objective by using South Carolina Pregnancy Risk Assessment and Monitoring System (PRAMS), 2000-2003 data linked to the 2000 U.S. census data. We used multilevel logistic regression analysis to estimate the adjusted odds ratio for different models. Results: Maternal stress was significantly associated with increased risks of low birth weight and preterm deliveries. Neighborhood high poverty and low education (upper quartiles) were independently associated with low birth weight but not preterm deliveries and stress appeared as a partial mediator of neighborhood effects on birth outcomes. The interaction models showed that the relationship between stress and LBW or PTB was modified by neighborhood exposures with risks being higher for infants born in disadvantaged neighborhoods. Conclusions: Effects of maternal stress on birth outcomes may be different for mothers living in different neighborhood contexts. Therefore, investigations that fail to examine places of residence would most likely not identify mothers at risk of low birth weight or preterm births. Clinicians seeking to improve birth outcomes need to target both places of residence and specific mediating or moderating factors associated with deprived neighborhoods of mother's residence.