Understanding of the importance of addressing trauma in health care is increasing rapidly. Health care providers may be actively seeking ways to address trauma sequelae affecting their patients with a trauma-informed continuum of care. Such a continuum includes a universal approach, targeted interventions (ie, practices and programs), and specialist treatment for posttraumatic stress disorder (PTSD), as well as responses to historic and intergenerational trauma. Client presentations and their needs are highly individualized. Therefore, an understanding of prominent theories of what causes PTSD may assist perinatal care professionals in adapting their practice to be trauma-informed and trauma-specific. The purpose of this article is to review 4 theories of PTSD relevant to perinatal practice and present an evidence-based practice framework that encourages collaborative choices consistent with client values and preferences. A brief summary of current evidence-based PTSD treatment guidelines is presented.