Substance use in pregnancy is common; nearly one of five of pregnant individuals have past-month nicotine, alcohol, or illicit substance use, and more than one in 10 meet criteria for a substance use disorder (SUD). Substance use disorders are among the most stigmatized and poorly understood medical conditions, particularly in the perinatal period. The obstetrician–gynecologist (ob-gyn) is a critical member of the health care and social support team for pregnant and postpartum individuals with SUD. Yet, many do not feel knowledgeable in screening and treating SUD, hampering efforts to identify and treat this population. In this review, we focus on practices that ob-gyns can incorporate into daily care. We start with the unique vulnerabilities of the perinatal period and discuss overdose as a leading cause of maternal death in the United States. We then review the basic tenets of addiction medicine including person-centered language and current medical terminology as well as best practices for substance use screening. We provide a review of maternal, fetal, and child effects of the most common substances including tobacco, alcohol, cannabis, opioids, stimulants, and benzodiazepines and their respective treatment recommendations, so that ob-gyns can incorporate basic addiction management into their daily practice.