RecruitingBehavioural interventionTreatment for Antepartum Posttraumatic Stress Disorder/PTSD StudyThe majority of women with perinatal posttraumatic stress disorder (PTSD) do not receive mental health treatment despite the documented associations between PTSD and adverse pregnancy outcomes; this is likely due to workforce shortages, lack of data on the effectiveness of existing evidence-based treatment for PTSD in usual care obstetrics settings, and patient-level barriers to engagement such as stigma. The proposed study is a randomized controlled trial, which will examine the effectiveness of a brief evidence-based treatment for PTSD (i.e., Written Exposure Therapy) during pregnancy and the non-inferiority of delivery of this treatment by community health workers vs. delivery by mental health clinicians.