Endocrine disrupting chemicals mixture and pregnancy glucose levels among women from a fertility clinic

Abstract

TPS 743: Health effects in pregnancy, Exhibition Hall, Ground floor, August 26, 2019, 3:00 PM - 4:30 PM Background/Aim: Endocrine disrupting chemicals (EDCs) have been linked to pregnancy complications such as gestational diabetes (GDM). As individuals are exposed to multiple chemicals simultaneously, investigating EDCs as a mixture is required to provide a more realistic assessment. We evaluated the association between pregnancy exposure to EDC mixture and glucose levels in the late second trimester of pregnancy, an established risk factor of GDM. Methods: We used data from 295 women in the Environment and Reproductive Health (EARTH) Study who had data available on 1st and/or 2nd trimester urinary concentrations of 19 EDCs, as well as late 2nd trimester glucose levels. Several methods were used to evaluate chemical mixtures including: weighted quantile sum (WQS) regression, for estimating exposures’ weights in contributing to the mixture-outcome association; shrinkage procedures (LASSO/elastic net) and Bayesian Kernel Machine Regression (BKMR), for variable selection. The 19 chemicals (3 parabens, triclosan, 11 phthalate metabolites, bisphenol A, benzophenone-3, 2,4-dichlorophenol, 2,5-dichlorophenol) concentrations were adjusted for specific gravity and log transformed. All analyses were adjusted for race, education, BMI, age, physical activity, smoking, and infertility diagnosis. A final linear regression model mutually including the selected exposures was further estimated. Results: Focusing on early 2nd trimester exposures, the following chemicals were identified as potential predictors of higher glucose by at least 2 statistical approaches: bisphenol-A, 2,4-dichlorophenol (2,4D), monoethyl phthalate (MEP), and the molar sum of four di(2-ethylhexyl) phthalate metabolites (∑DEHP). When fitting a final model that included these chemicals, suggestive positive associations were observed (e.g., β=2.2 mg/dL for (a unit increase in) log(2,4D), β =5.4 mg/dL for log(MEP), β =3.5 mg/dL for log(∑DEHP)). Analyses on 1st trimester exposures showed similar results. Conclusion: By evaluating EDCs as an environmental mixture, we identified relevant potential risk factors providing important insights in understanding the relationship between this class of chemicals and pregnancy glucose levels.