['To investigate associations between serum bisphenol A (BPA) concentrations and follicular response to exogenous ovary stimulation.', 'Fasting serum was prospectively collected on the day of oocyte retrieval and assessed for unconjugated BPA using high-performance liquid chromatography with Coularray detection. Multivariable linear regression and negative binomial regression were used to assess associations between concentrations of BPA and outcome measures. Models were adjusted for race/ethnicity, antral follicle count at baseline, and cigarette smoking.', 'A reproductive health center.', 'Forty-four women undergoing IVF.', 'None.', 'Peak E(2) level and the number of oocytes retrieved during IVF.', 'The median unconjugated serum BPA concentration is 2.53 ng/mL (range = 0.3-67.36 ng/mL). Bisphenol A is inversely associated with E(2) (β = -0.16; 95% confidence interval = -0.32, 0.01), as well as with E(2) normalized to the number of mature-sized follicles at the hCG trigger (β = -0.14; 95% confidence interval = -0.24, -0.03). No association is observed for BPA and the number of oocytes retrieved (adjusted risk ratio = 0.95; 95% confidence interval = 0.82, 1.10).'] Does bisphenol A exposure reduce the estradiol response to gonadotropin stimulation during in vitro fertilization?