In utero effects of maternal phthalate exposure on male genital development

Background Phthalates are used extensively in commercial and personal care products and maternal exposure is ubiquitous. Phthalates are anti‐androgenic, but the potential effects of phthalates on male penile development have not been assessed in utero. Objective The study aims to investigate the association between early pregnancy phthalate exposure and fetal penile development, overall and by race. Methods Prospective cohort study of women with singleton pregnancies presenting for prenatal ultrasound between 18 and 22 weeks' gestation. Maternal urine samples were assayed for eight phthalate monoester metabolites. We used maternal phthalate levels at 18 to 22 weeks' gestation as predictors of fetal size using multiple linear regression models, adjusted for fetal gestational age, maternal age, race, smoking, and education. We incorporated a phthalate by race interaction into a second set of regression models. Results We detected statistically significant race interactions for continuous phthalates with penile width. Race interactions were also suggested for penile length and volume using tertiles of phthalates with point estimates generally positive for whites and negative for African Americans. Conclusion Penile development is significantly influenced by race, and the impact of maternal phthalates on penile measurements also varies by race. Maternal phthalate exposure can adversely affect in utero penile growth and development, especially among African Americans. What's already known about this topic? Phthalates are anti‐androgenic and have the potential to adversely affect reproductive organogenesis in males. What does this study add? Phthalate interactions by race suggest a greater vulnerability to endocrine disrupting chemicals among African Americans compared with whites.