Substance use and substance use disorders (SUDs) among pregnant and postpartum individuals have risen dramatically, necessitating enhanced clinician education and intervention strategies. This expert review offers obstetricians and gynecologists (OBGYNs) a comprehensive overview of substance use during the prenatal and postpartum periods. We discuss the epidemiology, maternal and fetal adverse effects, as well as treatment approaches for major substances: nicotine, cannabis, alcohol, benzodiazepines, stimulants, and opioids. Additionally, we address the ethical and legal implications of substance use during pregnancy and emphasize the importance of equitable and non-stigmatizing care. By integrating evidence-based practices, we aim to support OBGYNs in providing optimal care for pregnant and postpartum individuals affected by SUDs.