Perinatal opioid use disorders negatively impact maternal and neonatal outcomes and are a public health problem of increasing severity. More than half of women with a substance use disorder have a history of posttraumatic stress disorder that, if not adequately addressed, can impede substance use disorder treatment. This case report describes complexities in the treatment of a pregnant woman with opioid use disorder and posttraumatic stress disorder and reviews the psychotherapeutic and pharmacologic approaches available to treat these co-occurring disorders in pregnancy. This case demonstrates the importance of early screening and intervention for co-occurring posttraumatic stress disorder in pregnant women who use substances in a closely coordinated, multidisciplinary approach to improve outcomes for women and their infants.