Here is the design of a clinical trial:

Official Title: Effectiveness of a Mindfulness and Compassion Group Intervention Applied to Pregnant Women and Their Partners to Decrease Stress, Negative Affect and Depression During Pregnancy and Breastfeeding. Controlled and Randomized Study

Included conditions:
- Pregnancy, Childbirth and Postpartum

Study Armgroups:
- {'label': 'Experimental', 'type': 'EXPERIMENTAL', 'description': 'TAU + mindfulness applied face to face 8 sessions of 120 minutes/session Mindfulness and Compassion based intervention applied in groups of 12-15 people in traditional format. Written material and sound recordings will be offered as support elements. The estimated duration of the face to face program is two months.', 'interventionNames': ['Behavioral: Mindfulness']}
- {'label': 'No intervention', 'type': 'NO_INTERVENTION', 'description': 'Usual medical treatment (TAU) In this group the midwife will apply the usual treatment (childbirth education class in the third trimester of pregnancy).'}

Interventions:
- {'type': 'BEHAVIORAL', 'name': 'Mindfulness', 'description': 'TAU + mindfulness applied face to face 8 sessions of 120 minutes/session Mindfulness and Compassion based intervention applied in groups of 12-15 people in traditional format. Written material and sound recordings will be offered as support elements. The estimated duration of the face to face program is two months.', 'armGroupLabels': ['Experimental']}

Primary Outcomes:
- {'measure': 'Edinburgh postnatal depression scale (EPDS)', 'description': 'In the mindfulness and compassion based intervention group', 'timeFrame': 'Baseline'}
- {'measure': 'Edinburgh postnatal depression scale (EPDS)', 'description': 'In the TAU control group', 'timeFrame': 'Baseline'}
- {'measure': 'Edinburgh postnatal depression scale (EPDS)', 'timeFrame': 'Post-treatment 8 weeks from baseline in intervention group'}
- {'measure': 'Edinburgh postnatal depression scale (EPDS)', 'timeFrame': 'Post-treatment 8 weeks from baseline in TAU control group'}
- {'measure': 'Edinburgh postnatal depression scale (EPDS)', 'timeFrame': 'Post-partum 3 months follow up in 8 weeks intervention group'}
- {'measure': 'Edinburgh postnatal depression scale (EPDS)', 'timeFrame': 'Post-partum 3 months follow up in TAU control group'}
- {'measure': 'Edinburgh postnatal depression scale (EPDS)', 'timeFrame': 'Post-partum 6 months follow up in 8 weeks intervention group'}
- {'measure': 'Edinburgh postnatal depression scale (EPDS)', 'timeFrame': 'Post-partum 6 months follow up in TAU control group'}

Please estimate the sample size based on the assumption: 
Statistical power of 80%, a 5% significance level, a local alpha of 0.017 in the first test using Benjamini-Hochberg's procedure, and a dropout rate in the range of 15%-20%.
Sample size
        The sample size estimation was based on the expectation of a moderate standardized mean difference between groups on depressive symptoms at post-birth of dâ=â0.59. Like the protocol that will be used in the present study, this effect size was found in a recent RCT that used a modified MBCP program [24] compared to a TAU active standard childbirth preparation course with no mindâbody components. This effect size is also similar to that obtained in other studies using other programs [44], a pilot study evaluating the effectiveness of MBCE [33], a cohort study assessing the MindBabyBody program [34], and a brief pilot adaptation based upon the MBCP program [9]. Considering a statistical power of 80%, a 5% significance level in a between-group interaction with a local alpha of 0.017 in the first testâusing BenjaminiâHochbergâs procedureâand a dropout rate in the range of 15%â20%, as has been observed in these types of studies [45], 61 participants are needed in each group, for a total sample size of 122 women.