OBJECTIVE: To evaluate if antimüllerian hormone (AMH) is associated with pregnancy loss. DESIGN: Prospective cohort study within a block-randomized, double-blind, placebo-controlled trial of low-dose aspirin. SETTING: Not applicable. PATIENT(S): Women (n = 1,228) were of ages 18-40 years with a history of one to two pregnancy losses and were actively attempting pregnancy without fertility treatment. INTERVENTION(S): Not applicable. MAIN OUTCOME MEASURE(S): Pregnancy loss. RESULT(S): Relative risks (and 95% confidence interval [CIs]) of human chorionic gonadotropin (hCG)-detected and clinical pregnancy loss were assessed with the use of log binomial models with robust variance and inverse probability weights adjusted for age, race, body mass index, income, trial treatment assignment, parity, number of previous losses, and time since most recent loss. AMH levels were defined as: low (3.5 ng/mL; n = 483). Of the 1,202 women with baseline AMH data, 19 (17.3%) with low AMH experienced a clinical loss, compared with 61 (11.4%) with normal AMH and 50 (11.8%) with high AMH levels. Low or high AMH levels, compared with normal AMH, were not associated with clinical loss. Results for hCG-detected pregnancy loss mirrored those of clinical loss. CONCLUSION(S): AMH values were not associated with hCG-detected or clinical pregnancy loss in unassisted conceptions in women with a history of one to two previous losses. Our data do not support routine AMH testing for prediction of pregnancy loss. CLINICAL TRIAL REGISTRATION NUMBER: NCT00467363.