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BACKGROUND/OBJECTIVES: Pregnant women are exposed to multiple phthalates and their replacements, which are endocrine disrupting chemicals associated with adverse maternal and child health outcomes. Identifying maternal characteristics associated with phthalate/replacement exposure during pregnancy is important. METHODS: We evaluated 13 maternal sociodemographic and lifestyle factors, enrollment year, and conception season as determinants of exposure biomarkers of phthalates and their replacements in 482 pregnant women from the Illinois Kids Development Study (I-KIDS, enrolled 2013–2018). We quantified 19 phthalate/replacement metabolites in pools of five first-morning urines collected across pregnancy. K-means clustering identified women with distinct patterns of biomarker concentrations and principal component analysis (PCA) identified principal component (PC) profiles of biomarkers that exist together. We used multivariable regression models to evaluate associations of predictors with identified k-means clusters and PCs. RESULTS: K-means clustering identified two clusters of women: 1) low phthalate/di(2-ethylhexyl) terephthalate (∑DEHTP) and 2) high phthalate/∑DEHTP biomarker concentrations. PCA identified four PCs with loadings heaviest for biomarkers of plasticizer phthalates [di-isononyl, di-isodecyl, di-n-octyl phthalates] (PC1), of other phthalates [dibenzyl, di-n-butyl, di-iso-butyl phthalates] (PC2), of phthalate replacements [∑DEHTP, di(isononyl) cyclohexane-1,2-dicarboxylate (∑DiNCH)] (PC3), and of monoethyl phthalate (PC4). Overall, age, marital status, income, parity, pre-pregnancy BMI, caffeine intake, enrollment year, and conception season were independently associated with k-means cluster membership and at least one PC. Additionally, race/ethnicity, education, employment, pregnancy intention, smoking status, alcohol intake, and diet were associated with at least one PC. For instance, women who conceived in the spring, summer, and/or fall months had lower odds of high phthalate/∑DEHTP cluster membership and had lower plasticizer phthalate, phthalate replacement, and MEP PC scores. CONCLUSIONS: Conception season, enrollment year, and several sociodemographic/lifestyle factors were predictive of phthalate/replacement biomarker profiles. Future studies should corroborate these findings, with a special focus on replacements to which pregnant women are becoming increasingly exposed.

BACKGROUND: Polybrominated diphenyl ethers (PBDEs) are persistent environmental pollutants used as flame retardants. Gestational PBDE exposure has been associated with a variety of behavior problems in children, but little is known about its impact into adolescence, particularly on social skills, which are important for achieving social competence, establishing identity, and forming lasting relationships. OBJECTIVE: We investigated associations between gestational exposure to PBDEs and social skills and problem behaviors in early adolescence in a longitudinal pregnancy and birth cohort in Cincinnati, Ohio (recruited 2003–2006). METHODS: We measured maternal serum concentrations of five PBDE congeners during gestation. At age 12, we collected social skills and problem behaviors scores from 243 adolescents and their caregivers using the Social Skills Improvement System (SSiS). We used multivariable linear regression models to estimate associations between maternal PBDE concentrations and SSiS outcomes, controlling for potential covariates. We report associations for the five congeners and a summary exposure variable (∑(5)BDE: the sum of BDE- 28, 47, 99, 100, and 153, n=197). RESULTS: We found sex-specific associations of ∑(5)BDE concentrations with adolescent-reported Problem Behaviors (∑(5)BDE × sex p(int)=0.02) and caregiver-reported Social Skills (∑(5)BDE × sex p(int)=0.02) despite higher ∑(5)BDE exposure among females (Male GM=35.30 ng/g lipid, GSE=1.09; Female GM=40.15 ng/g lipid, GSE=1.10). In sex-stratified models, log(10) transformed data revealed increased maternal ∑(5)BDE concentration among males was associated with decreased caregiver-reported Social Skills composite score (β=−10.2, 95% CI: −19.5, −1.0), increased adolescent-reported Problem Behaviors composite score (β=12.1, 95% CI: 5.4, 18.8), and increased caregiver-reported Problem Behaviors composite score (β=6.2, 95% CI: 0.7, 11.7). Further analysis on SSiS subscales revealed similar patterns in significant associations among males. There were no statistically significant associations in stratified models among females. DISCUSSION: We found gestational PBDE exposure in males was associated with poorer behavioral outcomes, extending previous findings among this cohort into early adolescence.