Study Results
The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.
Basic Information
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NOT_YET_RECRUITING
NA
112 participants
INTERVENTIONAL
2025-07-05
2026-07-05
Brief Summary
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Detailed Description
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Participants are randomized into two groups using a permuted block method:
HRT Group (Control): Estradiol valerate is initiated at 4 mg/day on day 2 of the menstrual cycle and is adjusted to 8 mg/day based on endometrial thickness. Once the endometrial thickness reaches ≥8 mm, progesterone supplementation is started (400 mg vaginal suppositories twice daily and 50 mg intramuscular injections daily) for 5 days before blastocyst transfer.
Natural Cycle Group: A transvaginal ultrasound is performed on cycle day 2 or 3 to rule out ovarian cysts and confirm an endometrial thickness \<5 mm. If eligible, patients are monitored from day 8 onward. Ovulation is tracked by assessing dominant follicle growth (≥15 mm), LH surge (≥17 IU/L), and serum progesterone (\>1.5 ng/mL). Once ovulation is confirmed and endometrial thickness reaches ≥7 mm, FET is scheduled for 6 days post-LH surge or 5 days post-follicle collapse. Serum progesterone is measured one day before transfer; if \<10 ng/mL, 400 mg/day progesterone is administered.
Embryos are cultured in Blastocyst medium (Origio, Denmark) and assessed daily. High-quality embryos (Grade A) are defined by a 4-cell stage on day 2, a 7-8 cell stage on day 3, uniform cell size, and \<20% fragmentation. Blastocyst grading follows Gardner's criteria. One or two top-quality embryos are transferred using a Cook catheter under abdominal ultrasound guidance. If no blastocyst is available by day 5, the most advanced embryo is transferred.
Conditions
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Study Design
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RANDOMIZED
PARALLEL
TREATMENT
NONE
Study Groups
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natural cycle group
A transvaginal ultrasound is performed on cycle day 2 or 3 to rule out ovarian cysts and confirm an endometrial thickness \<5 mm. If eligible, patients are monitored from day 8 onward. Ovulation is tracked by assessing dominant follicle growth (≥15 mm), LH surge (≥17 IU/L), and serum progesterone (\>1.5 ng/mL). Once ovulation is confirmed and endometrial thickness reaches ≥7 mm, FET is scheduled for 6 days post-LH surge or 5 days post-follicle collapse. Serum progesterone is measured one day before transfer; if \<10 ng/mL, 400 mg/day progesterone is administered
No interventions assigned to this group
Hormone Replacement Therapy (HRT)
hormone replacement therapy (HRT) group
Estradiol valerate is initiated at 4 mg/day on day 2 of the menstrual cycle and is adjusted to 8 mg/day based on endometrial thickness. Once the endometrial thickness reaches ≥8 mm, progesterone supplementation is started (400 mg vaginal suppositories twice daily and 50 mg intramuscular injections daily) for 5 days before blastocyst transfer.
Interventions
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hormone replacement therapy (HRT) group
Estradiol valerate is initiated at 4 mg/day on day 2 of the menstrual cycle and is adjusted to 8 mg/day based on endometrial thickness. Once the endometrial thickness reaches ≥8 mm, progesterone supplementation is started (400 mg vaginal suppositories twice daily and 50 mg intramuscular injections daily) for 5 days before blastocyst transfer.
Eligibility Criteria
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Inclusion Criteria
Maternal age between 18 and 42 years
Normal intrauterine cavity confirmed by pretreatment ultrasound or hysteroscopy
Body Mass Index (BMI) less than 30 kg/m²
No ovulation disorders
Exclusion Criteria
Withdrawal of patient consent to continue treatment
Failure of dominant follicle development (in natural cycle group)
Inadequate endometrial response for transfer
No endometriosis grade 3 or higher
The participant provided written informed consent
18 Years
42 Years
FEMALE
Yes
Sponsors
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Malihe Mahmoudinia
OTHER
Responsible Party
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Malihe Mahmoudinia
Associate Professor of obstetrics & Gynecology, Fellowship of infertility, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
Central Contacts
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Other Identifiers
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IR.MUMS.IRH.REC.1403.221
Identifier Type: -
Identifier Source: org_study_id
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