Here is the design of a clinical trial:

Official Title: Happy Mother-Healthy Baby: An Anxiety-focused Early Prenatal Intervention for the Prevention of Common Mental Disorders in Pakistan

Included conditions:
- Postpartum Depression
- Small for Gestational Age at Delivery
- Preterm Birth
- Anxiety
- Birth Weight

Study Armgroups:
- {'label': 'Cognitive Behavioral Therapy Intervention for Anxiety', 'type': 'EXPERIMENTAL', 'description': "Pregnant women experiencing anxiety randomized to the Happy Mother Healthy Baby (HMHB) intervention receive a CBT-based psychosocial intervention (with six core and up to six booster sessions). HMHB is a facility-based intervention delivered by non-specialist providers. It is aimed to raise psychosocial awareness and facilitate positive change inter personal wellbeing, social support, and bonding with their baby during pregnancy. It addresses with relapse prevention, planning for the baby's arrival, and in management of emotional challenges in the early postnatal period. Family member/s will be invited to attend 3 core sessions.", 'interventionNames': ['Behavioral: Cognitive Behavioral Therapy Intervention for Anxiety']}
- {'label': 'Enhanced Usual Care', 'type': 'NO_INTERVENTION', 'description': 'Women randomized to the control group will receive enhanced usual care (EUC). The World Health Organization (WHO) recommends 8 antenatal visits for a positive pregnancy experience, the number of visits our EUC control group participants will receive (depending on their gestational week). Usual care will also be enhanced by hospital staff receiving additional training in mental health treatment and counseling. Reminder calls were given, provider visits were facilitated (shorter wait times), and transportation to assist participants in attending appointments and medically indicated ultrasounds were paid for (as in the intervention group).'}

Interventions:
- {'type': 'BEHAVIORAL', 'name': 'Cognitive Behavioral Therapy Intervention for Anxiety', 'description': 'Happy Mother Healthy Baby (HMHB) is a CBT-based psychosocial intervention for expectant women experiencing anxiety during their pregnancy. Strategies such as empathetic listening, thought challenging, behavior activation, problem management, take-home exercises, and family involvement are employed by HMHB.', 'armGroupLabels': ['Cognitive Behavioral Therapy Intervention for Anxiety']}

Primary Outcomes:
- {'measure': 'Number of Participants With Combined Common Mental Disorders (CMDs, i.e. Anxiety and Depression).', 'description': 'Data reported is the number of participants with Common Mental Disorders (CMDs), which is defined as a woman having either high anxiety or clinical depression at the time of follow-up. Both CMDs, anxiety was indicated by moderate to severe symptoms on the anxiety portion of the Hospital and Anxiety Scale (HADS). A cutoff of \\>10 was used as the threshold for moderate to severe levels of anxiety. A Major Depressive Episode (MDE) was measured with the Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders (SCID), which is a semi-structured interview used to make major Axis I Diagnostic and Statistical Manual of Mental Disorders (DSM) diagnoses. Its scoring will be based on case or non-case basis.', 'timeFrame': '6 weeks postpartum'}

Please estimate the sample size based on the assumption: 
We assumed a significance level of 0.05 and aimed for 85% power to detect the reduction in CMDs. We also considered a 30% attrition rate post-enrollment. For SGA, we aimed for 90% and 80% power to detect specific reductions.
Sample size determination
        In our study, the unit of randomisation is an individual woman, with an equal number of women randomised to the intervention and control groups. We assumed a significance level of 0.05. Sample size calculations were based on Ï2 tests comparing outcome rates in the intervention and control groups. We assumed an outcome prevalence of CMDs (MDE and GAD) at 30%, which we considered conservative given that most estimates of prenatal depression in Pakistan are higher than this.3 4 39 44 Assuming this prevalence and considering a 30% reduction in CMDs as meaningful,1 45 46 we will need to measure this outcome in 840 pregnant women (420 in each arm) to achieve 85% power. Based on our prior research experience in Pakistan, we will overenrol to compensate for 30% attrition post enrolment; this attrition rate will require us to enrol 600 women per group in this study, for a total of 1200 women.
        This sample size of 420 outcomes per group provides ample power to detect important reductions in SGA, which we currently estimate to occur in approximately 47% of births. For example, we will have 90% and 80% power to detect reductions in SGA incidence of 23.7% and 20.2%, respectively. With the sample size of 420 per group, we will have about 85% power to detect a 21.6% relative reduction in SGA, if SGA in the population is 47%.