Cognitive Processing Therapy for Childbirth-Related Post-Traumatic Stress Disorder

Feasibility: Recruitment Rate

Feasibility will be evaluated using descriptive statistics to determine the practicality of conducting the study and delivering the intervention. Recruitment rates, reflecting the portion of individuals that express interest and enroll in the study, will provide information about our recruitment process and whether this is sufficient for conducting the study. This will be calculated as a percentage of the proportion of individuals who express interest in the study and subsequently enroll.

Feasibility: Eligibility Rate

Feasibility will be evaluated using descriptive statistics to determine the practicality of conducting the study and delivering the intervention, including the eligibility rate. Eligibility rate will be calculated as the proportion in percentage of screened individuals who meet inclusion and exclusion criteria.

Feasibility: Session Attendance

Feasibility will be evaluated using descriptive statistics to determine the practicality of conducting the study and delivering the intervention. Weekly session attendance will be used to assess engagement with treatment components. Session attendance will be calculated as the proportion of treatment sessions attended out of the total number of sessions.

Feasibility: Homework Completion

Feasibility will be evaluated using descriptive statistics to determine the practicality of conducting the study and delivering the intervention. Homework completion will be used to assess engagement with treatment components. Homework completion will be assessed as the proportion of assigned homework tasks completed during the intervention period.

The PTSD Checklist for DSM-5 (PCL-5)

The PTSD checklist, or PCL-5, screens individuals for PTSD by assessing the symptoms of PTSD outlined by the DSM-5. It is a 20-item self-report measure that requires users to rate each symptom statement on a scale from 0 (not at all) to 4 (extremely) to indicate how much they have been impacted by that symptom in the past month. For example, "In the past month, how much have you been bothered by repeated, disturbing dreams of the stressful experience?" During treatment, the PCL-5 will be completed on a weekly basis before each session, and the investigators will use the version that is the exact same but refers to symptoms in the past week rather than the past month. Final scores can range from 0-80 by summing item responses together, with higher scores indicating greater trauma symptoms.

City Birth Trauma Scale (CBTS)

The City Birth Trauma Scale is a self-report questionnaire designed to assess birth-related trauma symptoms and PTSD. It has 29 items that measure PTSD according to the diagnostic criteria of the DSM-5. The first two questions reflect whether the individual experienced a Criterion A traumatic event related to childbirth, asking whether there was belief of serious injury or death to self or baby during the labour, birth, or immediately afterwards. The remaining questions ask about DSM-5 PTSD-related symptoms during or immediately after an individual's labour and birth. It requires users to rate how frequently they experience each symptom statement on a scale of 0 (not at all), once, 2-4 times, or 5 or more times. Scores can range from 0 to 60, with higher scores indicating greater frequency of symptoms.

Edinburgh Postnatal Depression Scale (EPDS)

The EPDS is a 10-item self-report measure that assesses symptoms of depression during the perinatal period (Murray \& Cox, 1990). Items are scored on a 4-point scale ranging from 0 to 3, with higher scores reflecting greater depressive symptomatology. Scores can range from 0 to 30.The EPDS has demonstrated good sensitivity and specificity for a diagnosis of Major Depressive Disorder (MDD). Cut-off scores of 15 and 13 or higher have been suggested for detecting a probable diagnosis of MDD during pregnancy and the postpartum period, respectively (Matthey et al., 2006).

Generalized Anxiety Disorder 7-Item Scale (GAD-7)

The GAD-7 is a 7-item self-report measure that assesses anxiety symptom severity over a previous two-week period (Spitzer et al., 2006). Items are measured on a 4-point scale ranging from 0 ('not at all') to 3 ('nearly every day'). Scores can range from 0 to 21, with higher scores indicating greater severity of symptoms. A cut-off score of 10 or higher with sensitivity of 89% and specificity of 82% has been suggested for detecting a probable diagnosis of Generalized Anxiety Disorder (Spitzer et al., 2006). The GAD-7 has also been validated for use in perinatal samples (Simpson et al., 2014).