Objectives: Research on the effect of mindfulness-based cognitive therapy (MBCT) applied to postpartum mothers on the mother's mood and mother-infant interaction is a new and promising feld of research. However, the evidence on whether MBCT reduces stress and postpartum blues and improves mother-infant attachment and breastfeeding is inconclusive. The present study addresses this research question.

Design: A two-arm randomized controlled trial was conducted in 90 postpartum mothers.

This two-arm randomized controlled trial (RCT) was conducted in the postpartum mothers located in Edirne, between April and December 2022. During the intake, postpartum mothers were informed about the goals and setup of the study and intervention, and assessed for eligibility by a brief standardized interview. Postpartum mothers who fulfilled our criteria received an information letter and informed consent form, as well as the baseline questionnaire. Those postpartum mothers that provided written informed consent for participation were included in the study. Assessments in both groups were performed before randomization (i.e., baseline) and directly after the intervention period (i.e., post-measurement, approximately 2 months after baseline).

Randomization: Postpartum mothers were randomly assigned to an 8-week MBCT or control condition. A research assistant not actively involved in the design and data analysis of the study created a random distribution sequence and assigned participants to one of the two conditions (1:1 ratio).

Intervention: Mindfulness-Based Cognitive Therapy (MBCT) is a structured group intervention developed. The intervention consisted of eight weekly 2.5-hr sessions and one 3-hr silent session. The main aspects of the program; It included group meditation, cognitive-behavioral exercises, psycho-education, and daily homework. The intervention in our study closely followed the original manual, with several adaptations for the study group and purpose. First, psycho-education focused on the importance of recognizing personal feelings and the relationship between stress, postpartum blues, mother-infant attachment and breastfeeding symptoms, and stress management, stress, postpartum blues, mother-infant attachment and breastfeeding.

Control Condition: Postpartum mothers in the control condition were informed that they would receive MBCT after a waiting period of 2 months. Meanwhile, no psychological intervention was ofered.

Measures: The baseline questionnaire included questions about demographic, socioeconomic, obstetric, mood, and breastfeeding-specific information. Outcomes related to all stress, postpartum blues, mother-infant attachment, and breastfeeding were assessed at baseline and after therapy (on average, 2 months after baseline assessment).

Sample size calculation for the primary research question was performed based on a pilot study, which assessed pre- and post-measurement stres and depression levels in postpartum participating in a mindfulness program similar to MBCT, specifcally CALM Pregnancy as focused on training in formal mindfulness and informal mindfulness practices. The CALM Pregnancy program both involve eight weekly 2.5-hr sessions. Sessions included didactic presentations, group exercises, formal meditation practices, and leader-facilitated group inquiry and discussion. Formal practices included the body scan, mindful yoga, and sitting meditation. Informal mindfulness practices included mindfulness of everyday activities such as mindful eating and mindful walking. The intervention also incorporated the 3-min breathing space and cognitive approaches for developing alternative ways of responding to stress and anxiety symptoms. Given the similarities in the content, structure, and intensity of the two programs, the investigators used this pilot study for the sample size calculation. With a statistical power of 0.95 and an alpha of 0.05, 45 postpartum mothers patients were required per group (90 in total) to be able to detect diferences with an effect size of at least 0.50.

Inclusion Criteria:

• Volunteer to participate in the research,
• Over 18 years old,
• Participated in group sessions for 2,5 hours once a week for eight weeks,
• Mothers could read, write and speak Turkish.

Exclusion Criteria:

• Over 49 years old,
• The presence of serious cognitive, neurological, and psychiatric disorders that may preclude participation of postpartum mothers or require other treatment,
• Particularly psychotic complaints or a diagnosis of schizophrenia, neurological disorders including severe cognitive limitations,
• Substance use disorder, and acute suicidal thoughts or behaviors that may stress the mother,
• The presence of any congenital anomaly in the baby.

Postpartum mothers