According to the Diagnostic and Statistical Manual of Mental Disorders (fifth edition), substance use disorders include symptoms of dependence, as well as the harmful use of psychoactive substances such as alcohol, tobacco, cannabis, amphetamines, cocaine, opioids, and benzodiazepines. Prescription drugs are included in this category, as they are often used illicitly and in excess. The prevalence of substance use disorders in pregnancy, especially opioid use disorders, has risen dramatically in recent years and affects women of all racial, ethnic, geographic, and socioeconomic backgrounds. Maternal opioid use during the antepartum period increased 5-fold from 2000 to 2009,[1] with overdose deaths related to heroin up more than 300% over a 5-year period in the United States.[2] Pregnancy provides an opportunity to identify and treat women with substance use disorders, and OB/GYN hospitalists have a duty to provide comprehensive, ethically, and legally sound care to patients with these disorders. OB/GYN hospitalists, often as part of a multidisciplinary team, manage patients with substance use disorders during antepartum, intrapartum, and postpartum phases of pregnancy. OB/GYN hospitalists are also well positioned to lead their institutions in developing and implementing strategies to optimize outcomes for these patients and their newborns, such as screening protocols, educational programs, and processes to link patients to outpatient care.