OBJECTIVES: Accuracy of self-report regarding prescription medication use among pregnant women is largely unknown. Accurate self-reported information is needed for medication reconciliation purposes, clinical management, clinical teratology research, and monitoring of adherence. This study examines the accuracy of self-reported medication use by pregnant women for medications used chronically and episodically or intermittently during pregnancy.  METHODS: This was a cross-sectional analysis of data collected through the University of New Mexico (UNM) cohort study, “Safety of Medication and Perception of Teratogenicity” (SMART). Pregnant women were recruited from UNM prenatal care clinics and were asked to report all medications they took since their last menstrual period. The analysis was limited to women enrolled in the first year of the study who had at least one prescription for diabetes or opioid analgesics medications (representative of chronic and acute medication use, respectively). The accuracy of agreement between self-report and medical records for each medication class was estimated by simple (κ) and prevalence and bias adjusted (PABAK) kappa. Information from the medical records was used as the ‘gold-standard’. RESULTS: A total of 92 pregnant women were included in the analysis. Agreement for diabetes medications was near perfect (κ=0.87; PABAK=0.91); whereas poor-to-moderate concordance was observed for opioid analgesics (κ=0.29; PABAK=0.57). Among antidiabetic medications, concordance was highest for biguanides (κ=0.90; PABAK=0.93) and lowest for sulfonylureas (κ=0.83; PABAK=0.87); whereas among opioid analgesics, highest agreement was observed for strong agonists (κ=0.51; PABAK=0.56) and lowest for moderate/low agonists (κ=0.06; PABAK=0.59). CONCLUSIONS: This study suggests poor accuracy of self-report with respect to prescription medications used as short courses or intermittently during pregnancy. Therefore, in clinical studies assessing safety of such medications in pregnancy, self-reported information needs to be supplemented by other sources. Accuracy of self-report for medications used chronically is acceptable.