Comparison of Two Protocols in Frozen Embryo Transfer
For patients and families
In plain language
An automatic summary of structured registry data. It is an orientation aid, not a substitute for the official protocol or a physician assessment.
- What is being studied
- The protocol lists: hormone replacement therapy (HRT) group.
- Who it may be relevant to
- Registry conditions: IVF Outcomes. Basic parameters: 18 years — 42 years · Female.
- What needs checking
- Age, condition and sex are only basic indicators. Prior treatment, laboratory values and other mandatory requirements appear in the eligibility criteria below.
- Where it takes place
- Center list to be confirmed — check the primary protocol.
- Next step
- Save the trial, show it to the treating physician, and confirm current recruitment with the study center. Costs, documents and travel →
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Official title
Comparison of the Pregnancy Outcomes of Frozen Embryo Transfer in the Natural Cycle vs. Artificial Cycle
Overview
This randomized clinical trial evaluates two different endometrial preparation protocols-hormone replacement therapy (HRT) and natural cycle-for frozen embryo transfer (FET) in infertile women undergoing assisted reproductive technology (ART). The goal is to compare implantation, clinical pregnancy, and ongoing pregnancy outcomes.
Detailed description
This prospective, randomized controlled clinical trial is conducted on women aged 18 to 42 years undergoing frozen embryo transfer (FET) during in vitro fertilization (IVF) cycles. Eligible participants meet the inclusion criteria and provide written informed consent.
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.
Interventions
- Drug 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.
Primary outcome measures
- Clinical pregnancy rate [Time frame: 6 weeks post-transfer]
- Chemical pregnancy rate [Time frame: 12-16 days post embryo transfer]
Secondary outcome measures (6)
- Ongoing Pregnancy Rate [Time frame: At 20 weeks after embryo transfer]
- Early Miscarriage Rate [Time frame: Up to 12 weeks after embryo transfer]
- Late Miscarriage Rate [Time frame: up to 24 weeks gestation]
- Live Birth Rate [Time frame: At delivery, After 24 weeks gestation]
- Cycle Cancellation Rate [Time frame: Up to the day of embryo transfer]
- Pregnancy Complications [Time frame: through study completion, an average of 1 year]
Eligibility criteria
Inclusion criteria
Regular menstrual cycles
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
No embryos available for transfer (no embryo thawing)
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
Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.
Healthy volunteers: Yes
Study design
- Allocation
- Randomized
- Model
- Parallel assignment
- Masking
- Open label
- Primary purpose
- Treatment
Study locations
Center list to be confirmed — check the primary protocol.
Identifiers
NCT: NCT07003373 · IR.MUMS.IRH.REC.1403.221