The investigators will design, construct, and pilot a prototype of a trauma-informed online intervention, which will be called "SunnysideFlex," that functionally integrates a web-based intervention targeting skills to decrease symptoms of PTSD and better manage mood during and after pregnancy. SunnysideFlex will build upon the previously IRB-approved "Sunnyside" intervention which targeted skills to manage mood through an interactive website with didactic material and tools. Women in weeks 16-28 of their pregnancy who self-report symptoms of PTSD will be randomized to one of three study groups: (1) SunnysideFlex, (2) the original Sunnyside intervention (active control), or (3) treatment as usual (TAU). The SunnysideFlex intervention will consist of 6 weeks of trauma-informed online lessons during pregnancy and booster sessions at 2 weeks, 4 weeks, and 6 weeks postpartum. Outcomes will be measured at baseline, post-intervention, 6 weeks postpartum, and 12 weeks postpartum. SunnysideFlex has the potential to provide a novel paradigm for improving maternal and child health outcomes in high-risk, trauma-exposed women.

Inclusion Criteria:

• Female
• 18 years and older
• Pregnant and between 16-28 weeks gestation
• Are currently engaged in prenatal care with a healthcare provider (OB/GYN, nurse, midwife, etc.)
• Endorse a history of one or more potentially traumatic events meeting Diagnostic and Statistical Manual of Mental Disorders-5 (DSM-5) Criterion A for PTSD (i.e., "exposure to actual or threatened death, serious injury, or sexual violence," American Psychological Association [APA], p. 271) that is interpersonal in nature (e.g., sexual or physical assault, child abuse/maltreatment, witnessing family violence)
• Endorse a score of 33 or greater on the PTSD Checklist for DSM-5 (PCL-5)
• Have access to a broadband internet connection
• Able to read and speak English

Exclusion Criteria:

• Pregnant with multiples
• Have visual, hearing, voice, or motor impairment that would prevent completion of study procedures
• Have been diagnosed with a psychotic disorder, bipolar disorder, dissociative disorder, substance use disorder, or other diagnosis for which participation in this trial is either inappropriate or dangerous based on self-report
• Report currently being in an abusive or unsafe relationship
• Currently receiving treatment (medication or psychotherapy), or have an intention to resume antidepressant medication after delivery (i.e., women who discontinued their medication during pregnancy)