MON-695 - Early Pregnancy Exposome: Associations with Biological Response Markers and the Impact of Maternal BMI.

Physiological and metabolic adaptations crucial for the pregnancy progression and fetal development may also be susceptible to stressors like environmental exposures with maternal metabolic/hormonal milieu adding further complexity. High maternal BMI is a stressor as it perturbs the metabolic, inflammatory, and hormonal milieu. The impact of BMI on environmental chemical exposure burden and their impact on biological responses were investigated in first-trimester urine samples from 119 women (BMI ≥ 25 = 55, and BMI < 25 =64) that were part of the Michigan Mother-Infant Pair study. A validated multiclass, proficiency-tested assay was used to measure 96 chemicals from ten chemical classes and sixteen subclasses, as well as biomarkers of biological responses, such as oxidative stress markers (8-Iso Prostaglandin F2α and 4-Hydroxy-2-nonenal mercapturic acid) and glucocorticoid stress markers (cortisol and cortisone). Dimensionality reduction, partial least squares regression modeling, and bivariate correlation analysis were used to investigate the associations of chemicals with biological response markers. Pregnant women in both BMI groups reported similar lifestyles and use of consumer products. Women with higher BMI had lower urinary levels of several exposure classes and individual analytes compared to women with lower BMI. Importantly, the associations between exposure and biological response markers, and pregnancy outcomes differed by maternal BMI. Several exposure classes (phytoestrogens, polycyclic aromatic hydrocarbons, and insect repellant) showed a higher magnitude of positive associations with oxidative and glucocorticoid stress markers and other exposure classes as opposed to higher magnitude positive associations of UV filters, flame retardants and phthalates with oxidative stress markers in the lower BMI group. Higher urinary antimicrobial levels were associated with longer gestational age, irrespective of BMI. Several individual chemicals from phthalates, volatile organic compounds, and fungicides were negatively associated with birth weight in the high BMI group, while tobacco smoke metabolites were negatively associated with birth weight in the low BMI group. Factors that affect urinary excretion of chemicals and bioaccumulation associated with maternal adiposity may have contributed to maternal BMI-dependent differential impact of environmental exposures. A higher magnitude of positive associations among several exposure classes with other exposure classes and glucocorticoids is suggestive of increased susceptibility of high BMI women to the individual and combined effects of environmental exposures. This underscores the importance of incorporating maternal BMI into the evaluation of exposure burden and its effects on pregnant women, not merely as a covariate but as a factor that may actively shape biological responses.

*Unless otherwise noted, all abstracts presented at ENDO must not be released to the press or the public until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.*