Associations between social, biologic, and behavioral factors and biomarkers of oxidative stress during pregnancy: Findings from four ECHO cohorts

Background: Lower socioeconomic status (SES) and elevated psychosocial stress are known contributors to adverse pregnancy outcomes; however, biological mechanisms linking these factors to adverse pregnancy outcomes are not well-characterized. Oxidative stress may be an important, yet understudied mechanistic pathway. We used a pooled study design to examine biological, behavioral, and social factors as predictors of prenatal oxidative stress biomarkers. Methods: Leveraging four pregnancy cohorts from the Environmental influences on Child Health Outcomes (ECHO) Program spanning multiple geographic regions across the United States (U.S.) (N = 2082), we measured biomarkers of oxidative stress in urine samples at up to three time points during pregnancy, including 8-isoprostane-prostaglandin F_2α (8-isoPGF_2α), its major metabolite, 2,3-dinor-5,6-dihydro-15-F_2t-isoprostane, and prostaglandin F_2α (PGF_2α). Maternal age, pre-pregnancy body mass index, marital/partnered status, parity, and smoking status were included as biological and behavioral factors while race/ethnicity, maternal education, and stressful life events were considered social factors. We examined associations between each individual biological, behavioral, and social factor with oxidative stress biomarkers using multivariable-adjusted linear mixed models. Results: Numerous biological, behavioral, and social factors were associated with elevated levels of 8-isoPGF_2α, its major metabolite, and PGF_2α. Pregnant people who were current smokers relative to non-smokers or had less than a high school education relative to a college degree had 11.04% (95% confidence interval [CI] = −1.97%, 25.77%) and 9.13% (95% CI = -1.02%, 20.32%) higher levels of 8-isoPGF_2α, respectively. Conclusions: Oxidative stress biomarkers are elevated among pregnant people with higher socioeconomic disadvantage and may represent one pathway linking biological, behavioral, and social factors to adverse pregnancy and child health outcomes, which should be explored in future work.