Can a simple pill or natural timing improve IVF frozen embryo success?
NCT ID NCT07425990
First seen Jun 27, 2026 · Last updated Jun 27, 2026
Summary
This study tests whether preparing the uterus for frozen embryo transfer with a completely natural cycle or a modified cycle (with ovulation-triggering medication) works better. It also looks at adding letrozole tablets early in the cycle. About 120 women undergoing IVF will be randomly assigned to one of four groups. The goal is to see which approach leads to the highest chance of a confirmed pregnancy.
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Study facts
What this study's own registry entry says, in plain language.
- Phase
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Not a phased trial
Phase numbers describe drug development. The registry uses this when they do not apply, as it does for trials of devices, procedures or behaviour changes, and for observational studies.
- Participants
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About 120 people
The number the study aims to enrol. It can still change while the study runs.
- Expected to start
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Feb 2026
An estimate. Start dates often move.
- Expected to finish
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Mar 2027
An estimate. End dates often move.
- Lead sponsor
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Other sponsor
The registry's catch-all category, for sponsors it does not file as a company, a government agency, or a research network.
Who can take part
This study's own entry requirements. Only the study team can say for certain whether you qualify.
- Ages
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18 to 40 years
- Sex
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Female participants only
- Healthy volunteers
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Not accepted
This study is not open to healthy volunteers. The entry requirements below say who it is open to.
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Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.
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
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Conditions
The condition(s) this trial relates to.
As listed by the trial registrant
The condition terms exactly as the trial's registrant entered them.
How to take part
Only the study team decides who joins. These are the ways to reach them.
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The study's own enquiry address
This study publishes an address for enquiries. See it below .
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The places running it
1 site. The list below names each one and where it is.
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The official record
ClinicalTrials.gov lists the study team's own contact details, including names and phone numbers. We don't republish those.
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A doctor treating you
A doctor who knows your case can contact a study site on your behalf, and can tell you whether this study is worth pursuing at all.
Contacts and locations
Show contact details
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Genom att skicka in godkänner du våra Användarvillkor
Locations
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Specialized Gynecological Hospital "Ferona" Novi Sad
Novi Sad, 21000, Serbia
Contact Email: •••••@•••••
More trials for these conditions
Other studies related to the condition(s) this trial covers.
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- Do infertility treatments leave a metabolic mark on children?
- Can AI learn to spot endometriosis and fibroids on ultrasound?
- One shot instead of many: a simpler path to IVF egg retrieval?
- Can sex boost the odds of IVF success?
- IVF Needle-Free? oral pill tested as injection alternative