Feasibility Study: Self-guided iCBT for Mothers With Postpartum Depression.

• Data collection feasibility: measured as assessment completion
• Recruitment: measured as the total number of eligible participants, the number who completed the screening questionnaire, and the number of participants completing enrollment per month
• Experiences with the trial procedures: Post-intervention, all enrolled participants will participate in a semi-structured interview to evaluate their experiences with the trial procedures. A member of the research team will conduct the interviews.

The acceptability of the intervention will be assessed as a composite outcome consisting of:

• The Client Satisfaction Questionnaire (CSQ-8) will measure participants' satisfaction with the intervention. The questionnaire consists of eight items measured on a four-point scale, with total scores ranging from 8 to 32, with a higher number indicating greater satisfaction.
• The System Usability Scale (SUS) will measure participants' perceptions of the software's usability. The questionnaire consists of ten items measured on a five-point scale, with total scores ranging from 0 to 100, with a higher number indicating a better outcome.
• Experiences using the intervention: Post-intervention, participants in the intervention group will assess their experiences using the intervention and any issues related to it. A research team member will conduct semi-structured interviews with the participants.

Edinburg Postnatal Depression Scale (EPDS). It is a ten-item questionnaire, with scores ranging from 0 to 30. Higher scores indicate a worse outcome.

Negative Effects Questionnaire (NEQ). The questionnaire includes general information about the possibility of experiencing negative effects and is comprised of three separate parts: 1) "Did you experience this?" (yes/no) 2) "If yes-here is how negatively it affected me" (not at all, slightly, moderately, very, and extremely), and 3) "Probably caused by" (the treatment I received/other circumstances). The questionnaire contains 32 items, and how negatively the negative effect was is measured on a four-point Likert scale, ranging from 0-4 ("0" being minimum and "4" being maximum). Higher scores indicate a worse outcome.

The Automatic Thoughts Questionnaire (ATQ). The questionnaire consists of 30 items with a 5-point Likert scale. Scores range from 30 to 150, with higher scores indicating a worse outcome.

The Difficulties in Emotion Regulation Scale - 16-item version (DERS-16). The questionnaire consists of 16 items that assess emotion regulation difficulties. The total score ranges from 16 to 80, with higher scores indicating more difficulties with emotion regulation.

Danish Parental Stress Scale (DPSS). This is an 18-item measure of parental stress rated on a five-point scale (Strongly disagree, Disagree, Undecided, Agree, Strongly agree). The total score range is from 18 to 90, and a low score indicates less stress.

The Ages and Stages Questionnaire Social-Emotional Six Month (ASQ-SE-2): The questionnaire comprises 23 scored items with higher scores indicating a worse outcome.

World Health Organization disability assessment schedule 2.0 12 items: The questionnaire consists of 12 items, measured by a 5-point scale, with scores ranging from 12 to 60. Higher scores indicate a worse outcome.

Generalized Anxiety Disorder Assessment (GAD-7): This questionnaire screens levels of anxiety and consists of 7 items scored on a 0-3 scale from 0 to 21. Higher scores indicate a worse outcome.