Objective: To describe obstetrician-gynecologists' practices and attitudes related to opioid use among pregnant and postpartum women. Study Design: A 2017 cross-sectional survey assessed U.S. obstetrician-gynecologists' (n=462; response rate=34%) practices (management) and attitudes (knowledge, preparedness, confidence, barriers, and resources needed) related to opioid use among pregnant and postpartum women. Modified Poisson regression determined adjusted prevalence ratios (aPR) for advising medication assisted therapy (MAT) for pregnant women with opioid use disorder (OUD) by knowledge, confidence, and preparedness. Results: Of respondents, 33% usually or always advised MAT to pregnant women with OUD. Confidence in treating pregnant women who use opioids (aPR: 1.3, 95% CI: 1.0-1.8) and knowledge that substance use services were covered under the Affordable Care Act (aPR: 1.4, 95% CI: 1.1-1.8) were associated with advising MAT. Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use: