FET-LET-2x2: Clinical Pregnancy Rates After Frozen Embryo Transfer in Natural and Modified Natura… (NCT07425990) | Clinical Trial Compass
Not Yet RecruitingNot Applicable
FET-LET-2x2: Clinical Pregnancy Rates After Frozen Embryo Transfer in Natural and Modified Natural Cycles
Serbia120 participantsStarted 2026-02
Plain-language summary
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.
Who can participate
Age range
18 Years – 40 Years
Sex
FEMALE
See this in plain English?
AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.
Inclusion Criteria:
* 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
* Ability to provide written informed consent
Exclusion Criteria:
* 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
* Presence of clinically significant uterine abnormalities detected by ultrasound
* Inability or unwillingness to provide written informed consent
Questions worth asking your doctor
Bring these to your next appointment. They're a starting point for a shared conversation — not a sign you qualify or a recommendation to enrol.
1Based on my diagnosis and history, is this trial worth exploring for me — or is there a standard treatment we should try first?
2What does this trial's phase tell us about how much is already known about its safety and benefit?
3What would taking part actually involve for me — visits, tests, time, and travel?
4What are the known and possible risks or side effects I should weigh, and how would they be monitored?
5If this trial isn't the right fit, what other options or trials would you suggest I look into?
Generated to help you prepare — always confirm anything about your own eligibility and care with the study team and your doctor.
Questions for the trial coordinator
The trial coordinator is the person who runs the study day to day. These cover the practical side — logistics, costs, and what taking part would actually mean for your life. The study team confirms whether you meet the criteria; these are questions to ask, not a sign you qualify.
1What does taking part actually involve week to week — how many visits, where, and how long does each one take?
2What costs are covered by the study, and what might I have to pay for myself, including travel, parking, or time off work?
3What happens during screening, and what happens if the study team confirms I don't meet the criteria after those tests?
4Who pays for the scans, blood work, and other tests the trial requires — the study, my insurance, or me?
5How will being in the trial affect my regular care, and will my own doctor stay informed and involved?
6Can I leave the trial at any point if I change my mind, and what would happen to my care if I do?
A starting point for the conversation — always confirm anything about your own eligibility, costs, and care with the study team and your doctor.
What they're measuring
1
Clinical Pregnancy Rate
Timeframe: Approximately 4-6 weeks after embryo transfer.