Psychosocial stressors as modifiers of the associations between well-studied and understudied chemicals and birth outcomes in the ECHO Cohort.

Psychosocial stressors may exacerbate observed associations between environmental toxicants and adverse birth outcomes. However, studies have primarily focused on well-known compounds rather than a broader range of chemicals of concern. Pregnant women in this analysis had a prenatal urine sample analyzed for 113 well-studied and understudied chemical analytes, and at least one measure of psychosocial stress (N = 1566). We measured analytes from 10 chemical classes, including fungicides/herbicides, insecticides, halogenated phenols, organophosphorus flame retardants, benzophenones, bisphenols, parabens, antimicrobials, phthalates/alternative plasticizers, and polycyclic aromatic hydrocarbons. Principal component analysis was used to identify clusters of exposure patterns. Generalized Estimating Equation models assessed associations between principal components (PCs) and molar sums of each chemical class with birthweight z-scores and gestational age at birth, stratified by individual stressors (i.e., categorical adverse childhood experiences [ACEs; 0, 1-2, and 3-5]; binary prenatal perceived stress, depression, and anxiety). The PC reflecting higher exposure to all analytes (PC1) was negatively associated with birthweight z-scores only among those who experienced 3-5 ACEs compared with those with no ACEs (βPC1 = -0.08, 95 % confidence interval [CI] = -0.11, -0.05 for 3-5 ACEs; βPC1 = -0.01, 95 % CI = -0.05, 0.04 for 0 A CEs). Most phthalate molar sums were inversely associated with gestational age only among those with anxiety during pregnancy (e.g., βDINP = -0.29, 95 % CI = -0.41, -0.18 for anxiety-yes; βDINP = 0.23, 95 % CI = 0.01, 0.46 for anxiety-no). Findings suggest that certain psychosocial stressors modify associations between understudied chemicals and birth outcomes.