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Abstract
Background: Preterm birth (gestational age less than 37 weeks), the leading cause of infant morbidity and mortality worldwide, disproportionally impacts pregnancies in Puerto Rico. Psychosocial stress during pregnancy has been associated with adverse pregnancy outcomes, including preterm birth, and has not been explored in Puerto Rico. Oxidative stress may represent one possible mechanism linking psychosocial stress to preterm birth. The purpose of this dissertation is to (1) describe psychosocial stress during pregnancy in Puerto Rico and to explore the relationships between psychosocial stress measures; (2) investigate oxidative stress as a potential physiologic response to psychosocial stress in pregnancy; and (3) investigate psychosocial stress as a potentially modifiable risk factor for preterm birth. Methods: Data from this dissertation came from the Puerto Rico Testsite for Exploring Contamination Threats (PROTECT) pregnancy cohort. Psychosocial stress was measured using the Perceived Stress Scale, Life Experience Survey, Center for Epidemiologic Studies-Depression scale, ENRICHD Social Support Instrument, and two questions about neighborhood safety and quality adapted from the National Childrens Study. Descriptive statistics and bivariate analyses were used to examine associations between demographic characteristics and (1) psychosocial stress measures, (2) oxidative stress biomarkers and (3) preterm birth. Linear and logistic regression was used to examine associations between tertiles of psychosocial stress and oxidative stress biomarkers and preterm birth, respectively. Results: Approximatively 10% of the PROTECT analytic sample delivered preterm. Perceived stress, negative life experiences, and neighborhood perceptions influenced depression through multiple pathways. No associations were observed between other indices of psychosocial stress and oxidative stress biomarker concentrations. High compared to low psychosocial stress was not associated with increased odds of preterm birth across any of the measures examined. Conclusions: Our study examined associations between multiple measures of stress among a pregnant Puerto Rican population. Findings from our study highlight the complex relationship between psychosocial stress measures. In the PROTECT pregnancy cohort, increased psychosocial stress was not associated with increased biomarkers of oxidative stress or increased odds of preterm birth.