Here is the design of a clinical trial:

Official Title: A Randomized Trial Comparing the Effect of Immediate Versus Delayed Frozen-thawed Embryo Transfer Following a Stimulated IVF Cycle

Included conditions:
- Fertilization in Vitro
- Embryo Transfer

Study Armgroups:
- {'label': 'immediate group', 'type': 'OTHER', 'description': 'the intervention: immediate frozen-thawed embryo transfer (FET) which means FET will be performed in the first cycle following the stimulated IVF cycle', 'interventionNames': ['Other: immediate frozen-thawed embryo transfer']}
- {'label': 'delayed group', 'type': 'OTHER', 'description': 'the intervention: delayed frozen-thawed embryo transfer (FET) which means FET will be performed at least in the second cycle following the stimulated IVF cycle', 'interventionNames': ['Other: delayed frozen-thawed embryo transfer']}

Interventions:
- {'type': 'OTHER', 'name': 'immediate frozen-thawed embryo transfer', 'description': 'Frozen-thawed embryo transfer will be performed in the first cycle following the stimulated IVF cycle', 'armGroupLabels': ['immediate group']}
- {'type': 'OTHER', 'name': 'delayed frozen-thawed embryo transfer', 'description': 'Frozen-thawed embryo transfer will be performed at least in the second cycle following the stimulated IVF cycle', 'armGroupLabels': ['delayed group']}

Primary Outcomes:
- {'measure': 'ongoing pregnancy', 'description': 'viable pregnancy beyond gestation 12 weeks', 'timeFrame': 'viable pregnancy beyond gestation 12 weeks'}

Please estimate the sample size based on the assumption: 
Power of 0.8, type I error of 0.05, and a 10% drop-out rate.
Sample size estimation
          According to our data of the centre, the ongoing pregnancy rate per FET was about 30%. We hypothesise that a difference in the ongoing pregnancy rate of 10% between the immediate versus delayed groups as equivalence, the sample size required for a test of equivalence would be 329 in each arm to give a power of 0.8 and type I error of 0.05. Allowing 10% drop-out, 724 subjects or 362 in each arm will be needed.