FET-LET-2x2: Clinical Pregnancy Rates After Frozen Embryo Transfer in Natural and Modified Natural Cycles
Trial statusRecruiting
Trial phaseNot applicable
Trial typeInterventional
Biological sexFemale
Age18-40
SponsorUniversity of Novi Sad
About this trial
The goal of this clinical trial is to learn whether different natural approaches to preparing the uterus for frozen embryo transfer (FET) can improve pregnancy success in women undergoing in vitro fertilization (IVF) treatment.
The main questions it aims to answer are:
1. Is a completely natural menstrual cycle more successful than a natural cycle in which ovulation is triggered with medication when preparing for frozen embryo transfer? 2. Does taking a medication called letrozole at the beginning of the cycle improve pregnancy success compared to not taking it?
Researchers will compare four different approaches to see which one results in the highest chance of achieving a clinical pregnancy, confirmed by ultrasound.
Participants will:
* Be randomly assigned to one of four groups * Undergo monitoring with ultrasound and blood hormone tests during their menstrual cycle * In some groups, take letrozole tablets for a few days early in the cycle * In some groups, receive a hormone injection to help control the timing of ovulation * Undergo frozen embryo transfer at the appropriate time * Receive standard hormonal support after embryo transfer * Researchers will compare four different approaches to see which one results in the highest chance of achieving a clinical pregnancy, confirmed by ultrasound.
Eligibility criteria
This trial does not accept healthy volunteersQualifiers
Women aged 18 to 40 years
Regular menstrual cycles (26-35 days)
Scheduled for frozen embryo transfer (FET) in a natural menstrual cycle
Normal gynecological ultrasound findings without clinically significant uterine abnormalities
Disqualifiers
Use of preimplantation genetic testing (PGT) for the transferred embryo
Use of donor oocytes
Inadequate embryo survival after thawing, defined as loss of viability in more than 50% of blastomeres
Irregular menstrual cycles
Trial design
Design model
Factorial
Treatments tested in this trial
Letrozole (Aromatase Inhibitors)
DrugLetrozole 2.5 mg administered orally twice daily from cycle days 3-7 during the early follicular phase.
Choriogonadotropin alpha (r-hCG)
DrugRecombinant human chorionic gonadotropin (hCG) 250 mcg administered subcutaneously to trigger ovulation when follicular and endometrial criteria are met.
Progesterone
DrugLuteal phase support with either vaginal progesterone 200 mg twice daily or subcutaneous progesterone 25 mg once daily, initiated after ovulation (or 2 days after hCG trigger) and continued until 12 weeks of gestation if pregnancy occurs.
Treatment groups
120 Participants
are divided into 4 treatment groupsGroup A: True Natural Cycle Without LetrozoleExperimental treatment 1 intervention
Group B: True Natural Cycle With LetrozoleExperimental treatment 2 interventions
Group C: Modified Natural Cycle Without LetrozoleExperimental treatment 2 interventions
Group D: Modified Natural Cycle With LetrozoleExperimental treatment 3 interventions
Trial outcomes
Primary outcomes
1
Clinical Pregnancy Rate
Number of pregnancies with an ultrasound-confirmed gestational sac per embryo transfer.
Time frame
Approximately 4-6 weeks after embryo transfer.Secondary outcomes
1
Biochemical Pregnancy Rate
Number of pregnancies with elevated serum beta-human chorionic gonadotropin (β-hCG) levels measured two weeks after embryo transfer, per embryo transfer.
Time frame
Two weeks after embryo transfer.2
Implantation Rate
Number of ultrasound-confirmed gestational sacs divided by the number of embryos transferred.
Time frame
Approximately 4-6 weeks after embryo transfer.3
Miscarriage Rate
Pregnancy loss before 23 completed weeks of gestation, expressed per embryo transfer.
Time frame
Up to 23 weeks of gestation.Sponsors and contacts
Click on the lead sponsor to view all of their trials.
Source ClinicalTrials.gov