Here is the design of a clinical trial:

Official Title: Evaluating the Impact of a Common Elements-based Intervention to Improve Maternal Psychological Well-being and Mother-infant Interaction in a Low Resource Community Setting of Rural Pakistan

Included conditions:
- Maternal Distress
- Perinatal Depression
- Development Delay
- Language Delay
- Cognitive Developmental Delay
- Nutrition Poor
- Growth Delay
- Motor Delay
- Maternal Behavior
- Infant Development
- Infant Malnutrition
- Infant Behavior

Study Armgroups:
- {'label': 'Intervention arm', 'type': 'EXPERIMENTAL', 'description': 'Distressed mothers randomized to intervention arm will receive a common elements based integrated intervention that combines evidence based elements from packages of care addressing early stimulation, responsive feeding and perinatal depression. The integrated intervention is expected to a) improve mother psychological distress, b) improve family support, c) improve child development and d) promote mother-infant interaction.\n\nThe participants will receive 15 monthly sessions at home by lay health workers. First three sessions will be delivered to the participants in the third trimester of pregnancy, followed by 12 monthly sessions afterwards.', 'interventionNames': ['Behavioral: Intervention arm']}
- {'label': 'Treatment as Usual (TAU)', 'type': 'ACTIVE_COMPARATOR', 'description': 'The participants in the control arm will receive the routine monthly visits by the trained Lady Health Workers (LHWs) of their respective areas.', 'interventionNames': ['Other: Treatment as Usual']}

Interventions:
- {'type': 'BEHAVIORAL', 'name': 'Intervention arm', 'description': "In addition to the routine care delivered by Lady Health Workers (LHWs), the participants in the intervention arm will receive common elements based integrated intervention. The providers of the intervention are lay health workers who will be trained in the intervention using an online course. The lay health worker will complete the online training course in a group, with interactive group activities and role plays. Lay health workers will be supported online and in-person by the trainers in monthly supervision meetings. The lay health workers will deliver intervention to distressed mothers in 15 monthly sessions. The intervention consists of three modules including 1) mothers' well-being, 2) infant nutrition,early stimulation and breastfeeding and 3) mother-infant interaction.", 'armGroupLabels': ['Intervention arm']}
- {'type': 'OTHER', 'name': 'Treatment as Usual', 'description': 'The participants in the control arm will receive the routine visits by LHWs of their respective areas. The LHWs are trained to provide antenatal care and referral, immunization services and support to community mobilization, provision of family planning and basic curative care via door to door visits to the households of their allocated areas.', 'armGroupLabels': ['Treatment as Usual (TAU)']}

Primary Outcomes:
- {'measure': 'Observation of Mother and Child Interaction Tool (OMCI)', 'description': "Maternal responsive caregiving behaviours will be assessed using the Observation of Mother and Child Interaction (OMCI) tool . OMCI tool is based on responsive parenting framework proposed by Landry and colleagues. The research assistants will observe a live 5-minute mother-infant interaction while mother and infant will play together with a picture book. The tool comprises of 19 items covering maternal affect, maternal touch, maternal verbalization, sensitivity and contingent responses, scaffolding, language stimulation, focus, child affect, child focus, child's communication efforts, and mutual enjoyment. The scoring format is based on the frequency of the occurrence of behaviours with higher scores indicating more responsive interactions. The OMCI tool has been validated for use in similar population in Pakistan.", 'timeFrame': 'At 12-months postpartum'}

Please estimate the sample size based on the assumption: 
The assumptions include 80% power, 0.05 significance level, a two-sided hypothesis test, and a 20% attrition rate.
Sample size calculations
        The power calculations are based on one primary outcome, that is, motherâchild interaction on OMCI tool22 at 12 monthsâ postpartum. The scoring of tool is based on the frequency of the occurrence of responsive behaviours of mother with higher scores indicating more responsive interactions. The effect size for the present study was estimated based on the findings of a similar study conducted in Pakistan, where OMCI was used as one of the outcomes to evaluate the effect of responsive stimulation intervention on caregiverâchild interaction at 12 and 24âmonths postpartum.8 The findings of the study showed motherâchild dyads receiving responsive caregiving intervention had significantly higher mean scores on OMCI at 12 months (mean 32.3 (SD: 8.3) vs mean 27.1 (SD: 8.2), p<0.0001) than those who were allocated to control arm. Moreover, repeated-measures analysis showed that effects were sustained at 24âmonths. As the effect sizes for OMCI in Yousafzai et al 2015âs study ranged between 0.6 and 0.9; therefore, a conservative effect size of 0.4 (two-sides hypothesis) at 12âmonths post-partum was proposed in the present study. The effect size was calculated using the two-sided t-test. Assuming an effect size of 0.4, with 80% power, 0.05 significance and a two-sided hypothesis test and accounting for 20% attrition, we will need 250 caregiverâchild dyads (125 in each arm).