Here is the design of a clinical trial:

Official Title: Modified Downregulation for Women With Adenomyosis of the Uterus Prior to Frozen-thawed Embryo Transfer.

Included conditions:
- Adenomyosis

Study Armgroups:
- {'label': 'Standard downregulation with GnRH analogue', 'type': 'OTHER', 'description': "Participants in this arm will be assigned to the routine IVF protocol currently being used in the investigators' IVF unit, as outlined below, with one week of downregulation. Downregulation is the suppression of the ovaries during an IVF cycle in order to perform controlled ovarian stimulation and prevent premature ovulation.\n\nStart progesterone (Norethisterone 5mg twice daily orally) on day 14 of downregulation cycle and continue for 11 days. Start GnRH analogue (Buserelin 0.5ml subcutaneously once daily) on day 21 of downregulation cycle and reduce to 0.2ml on day 1 of bleed. Baseline scan on day 1 - 5 of bleed and start oestrogen (Progynova 2mg three times daily orally). Serial scanning from day 10 until endometrial thickness more than 8mm. Once endometrial thickness more than 8mm start progesterone (Cyclogest 400mg twice daily vaginally/rectally and Lubion 25mg twice daily subcutaneously) and proceed to embryo transfer on appropriate day for embryo age.", 'interventionNames': ['Drug: GnRH analogue downregulation', 'Other: Participant questionnaire']}
- {'label': 'Prolonged downregulation with GnRH analogue', 'type': 'EXPERIMENTAL', 'description': 'Participants in this arm will be exposed to an additional five weeks of downregulation using a GnRH analogue. Downregulation is the suppression of the ovaries during an IVF cycle in order to perform controlled ovarian stimulation and prevent premature ovulation.\n\nBaseline scan on day 1-5 of bleed and administer GnRH analogue (Leuprorelin acetate 3.75 mg subcutaneously single injection). 28 days later administer second dose of GnRH analogue (Leuprorelin acetate 1.875 mg subcutaneously), and 21 days later start oestrogen (Progynova 2 mg three times daily orally). Serial scanning from day 10 of oestrogen until endometrial thickness more than 8mm. Once endometrial thickness more than 8mm start progesterone (Cyclogest 400mg twice daily vaginally/rectally and Lubion 25mg twice daily subcutaneously) and proceed to embryo transfer on appropriate day for embryo age.', 'interventionNames': ['Drug: GnRH analogue downregulation', 'Other: Participant questionnaire']}

Interventions:
- {'type': 'DRUG', 'name': 'GnRH analogue downregulation', 'description': 'Downregulation is the suppression of the ovaries during an IVF cycle in order to perform controlled ovarian stimulation and prevent premature ovulation.\n\nParticipants will be exposed to one week of downregulation using a GnRH analogue in the standard downregulation arm and 6 weeks of downregulation using a GnRH analogue in the modified downregulation arm.', 'armGroupLabels': ['Prolonged downregulation with GnRH analogue', 'Standard downregulation with GnRH analogue']}
- {'type': 'OTHER', 'name': 'Participant questionnaire', 'description': 'Participant will be offered the opportunity to complete an adenomyosis symptom assessment questionnaire at the start of their treatment, and again two months after completion of treatment.', 'armGroupLabels': ['Prolonged downregulation with GnRH analogue', 'Standard downregulation with GnRH analogue']}

Primary Outcomes:
- {'measure': 'Clinical pregnancy rate', 'description': 'Clinical pregnancy is defined as an intrauterine pregnancy with a visible heart beat older than 6 weeks gestation.', 'timeFrame': '6 weeks after embryo transfer'}

Please estimate the sample size based on the assumption: 
80% power for detecting a 20% difference in the primary outcome at 5% significance level. Estimated prevalence of adenomyosis is 20.9% in benign gynaecology patients, with a higher prevalence among women seeking assisted conception with a history of subfertility.
Sample size
        Our previous observational studies suggest a clinical pregnancy rate of 42.7% in women with mild adenomyosis compared with 22.9% with moderate/severe adenomyosis.7 We theorise that the modified protocol will improve the chance of clinical pregnancy to similar levels in those with mild disease. We need to randomise 162 patients over 3 years to achieve 80% power for detecting a 20% difference in the primary outcome across those groups at 5% significance.
        Adenomyosis has an estimated prevalence of 20.9% in benign gynaecology patients,2 we estimate higher prevalence among women seeking assisted conception with a history of subfertility. Given our yearly 750 cycles of IVF/ICSI, we estimate a recruitment period of 3 years to achieve our target sample size.