MATERNAL EXPOSURE TO PHTHALATES AND MALE REPRODUCTIVE SYSTEM DEVELOPMENT IN THE OFFSPRING: RESULTS FROM A CANADIAN BIRTH COHORT STUDY
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Objectives: The primary objective of this thesis was to determine if maternal exposure to phthalates during the first trimester of pregnancy was associated with penile length (PL) or width (PW) at birth in full term singleton boys. Materials & Methods: In the MIREC (Maternal-Infant Research on Environmental Chemicals) prospective cohort study, 2001 pregnant women from 10 Canadian cities provided biospecimens for measurement of chemicals, including phthalates. Urinary concentrations of phthalate metabolites were measured in the first trimester of pregnancy. Total high and low molecular weight phthalates and Di-2-ethylhexyl phthalate(DEHP) concentrations were calculated based on the molar sum of their respective metabolites. At birth, multiple anthropometric measurements including PL and PW were conducted for 215 male offspring. Univariate and multivariate linear regressions were performed to study the association between penile measurements and maternal urinary concentrations of each phthalate metabolite and composite measures adjusting for potential confounders. Results: 170 term male singletons had complete data for analysis. On univariate analysis, no association was found between the individual levels of 7 phthalates metabolites, DEHP, low or high molecular weight phthalates and PL. On univariate analysis, PW showed a statistically significant inverse relationship with the log-transformed, specific gravity adjusted concentration of MCPP. On multivariate analysis controlling for confounders, a positive association between MEHP and PL was the only one to approach statistical significance. Conclusions: Based on our results, exposure to phthalates at levels representative of the Canadian population in the first trimester of pregnancy did not have a significant impact on PL/PW at birth in singletons born at term.