Embryo Transfer17FETNCT07088952
Triggering Ovulation at Follicle Size Smaller or Larger Than 17mm in a Modified Natural Cycle
A study testing Trigger at smaller folicular size in people with Embryo Transfer, run by Vida Recoletas Sevilla at 1 site in Spain.
Trial summary
The rise in frozen embryo transfer (FET) cycles within assisted reproductive technology (ART) has sparked the need to refine endometrial preparation protocols. The switch from hormone replacement cycles (HRT) to natural cycles, poses scheduling challenges onto laboratories, doctors and patients. Read more about this study
- Who is it for?
- Ages 18 to 50 years, women only
- Conditions the study is for
- Embryo Transfer
- What is being tested?
- Trigger at smaller folicular size
- Type of treatment
- Surgery or procedure
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 572 participants
- Where
- 1 siteSpain
- Study dates
- 22 Oct 2025to 30 May 2028
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 50 years
- Women only
- No healthy volunteers
- Adult
Who may be able to join
- At least one expanded blastocyst (regardless of its quality)
- Spontaneous menstrual cycles
- Consent to undergo frozen embryo transfer in a modified natural cycle
Who cannot join
- Abnormal uterine cavity
- Fluid in endometrial cavity
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Spain1 site, 1 recruiting
- Recruiting
Vida Recoletas Sevilla
Seville, Sevilla, 41092
Clara Palacio de Marco, MSc, +34954286274, vida.investiga@gruporecoletas.com
About this study
The rise in frozen embryo transfer (FET) cycles within assisted reproductive technology (ART) has sparked the need to refine endometrial preparation protocols. The switch from hormone replacement cycles (HRT) to natural cycles, poses scheduling challenges onto laboratories, doctors and patients. The modified natural cycle (mNC), offering more precision for scheduling, shows promise but lacks comprehensive data on the potential flexibility of triggering criteria that may allow to control timing in a wider range.
This prospective randomized study seeks to address this knowledge gap by evaluating the non-inferiority of triggering ovulation in mNC with follicle diameters of 13-16.9mm compared to the conventional 17-22mm.
The study aims to enhance the understanding of the impact of follicle size at ovulation in reproductive outcomes, optimize FET treatments providing a more flexible mNC protocol, and improve patient care in ART clinics.
- Conditions
- Embryo Transfer
- Being tested
- Trigger at smaller folicular size
- Keywords
- Natural Cycle, Frozen Embryo Transfer, Follicle Size, Pregnancy, Implantation
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Trigger at smaller folicular sizeProcedure or surgery
Trigger indicated at folicular diameter smaller than standard clinical practice, from 13mm to 16.9mm
| Study group | Role | What they receive |
|---|---|---|
| Control | No intervention | Trigger indicated as per standard clinical practice at folicular diameter of at least 17mm |
| Early trigger | Experimental | Trigger indicated at folicular diameter smaller than standard clinical practice Receives: Procedure: Trigger at smaller folicular size |
What is being measured
The primary outcome is the main question the study is designed to answer.
Pregnancy rate
Rate of positive pregnancies over total transfers performed, according to beta-test result
Measured: From embryo transfer up to 2 weeks later
Secondary outcomes (3)
Implantation rate
Implantation rate, defined as number of gestational sacs per embryos transferred
Measured: up to 8 weeks of gestational age
Cancelation rate
Number of cancelled embryo transfers per initiated endometrial preparation cycles. Transfer canceling implies end of study.
Measured: Perioperative/Periprocedural
Miscarriage rate
Number of miscarriages of any type registered after transfer during the study, per total number of transfers performed
Measured: From embryo transfer to delivery, up to 40 weeks
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted28 Jul 2025
- Study start22 Oct 2025
- Primary completion30 Jul 2027 (estimated)
- Study completion30 May 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Embryo TransferStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- Prospective open randomized parallel group 1:1 ratio
- Masking
- None (open label)
- Enrolment
- 572 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Vida Recoletas Sevilla
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07088952
- Sponsor's protocol ID
- 2310-SEV-02-MF
- Acronym
- 17FET
- Status last verified
- Jan 2026
- First submitted
- 17 Jun 2025
- Last updated
- 13 Jan 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: All IPD collected throughout the trial.
Study at a glance
From the registry record, last updated by the sponsor on 13 Jan 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Triggering Ovulation at Follicle Size Smaller or Larger Than 17mm in a Modified Natural Cycle
- ClinicalTrials.gov ID
- NCT07088952
- Acronym / sponsor ID
- 17FET / 2310-SEV-02-MF
- Conditions
- Embryo Transfer
- Keywords
- Natural Cycle, Frozen Embryo Transfer, Follicle Size, Pregnancy, Implantation
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 572 participants (estimated)
- Lead sponsor
- Vida Recoletas SevillaUniversity, hospital or other
- Study start
- 22 Oct 2025 (actual)
- Primary completion
- 30 Jul 2027 (estimated)
- Study completion
- 30 May 2028 (estimated)
- First posted
- 28 Jul 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The rise in frozen embryo transfer (FET) cycles within assisted reproductive technology (ART) has sparked the need to refine endometrial preparation protocols. The switch from hormone replacement cycles (HRT) to natural cycles, poses scheduling challenges onto laboratories, doctors and patients. The modified natural cycle (mNC), offering more precision for scheduling, shows promise but lacks comprehensive data on the potential flexibility of triggering criteria that may allow to control timing in a wider range.
This prospective randomized study seeks to address this knowledge gap by evaluating the non-inferiority of triggering ovulation in mNC with follicle diameters of 13-16.9mm compared to the conventional 17-22mm.
The study aims to enhance the understanding of the impact of follicle size at ovulation in reproductive outcomes, optimize FET treatments providing a more flexible mNC protocol, and improve patient care in ART clinics.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
- Model description
- Prospective open randomized parallel group 1:1 ratio
| Arm | Type | Receives |
|---|---|---|
| Control | No intervention | –Trigger indicated as per standard clinical practice at folicular diameter of at least 17mm |
| Early trigger | Experimental | Procedure: Trigger at smaller folicular sizeTrigger indicated at folicular diameter smaller than standard clinical practice |
Who may qualify
- Ages
- 18 to 50 years
- Sex
- Female only
- Healthy volunteers
- Not accepted
- Age groups
- Adult
Key inclusion criteria (3 listed)
- At least one expanded blastocyst (regardless of its quality)
- Spontaneous menstrual cycles
- Consent to undergo frozen embryo transfer in a modified natural cycle
Key exclusion criteria (2 listed)
- Abnormal uterine cavity
- Fluid in endometrial cavity
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Trigger at smaller folicular sizeTrigger indicated at folicular diameter smaller than standard clinical practice, from 13mm to 16.9mm | Procedure or surgery | Early trigger |
Primary outcome
Pregnancy rate
Time frame: From embryo transfer up to 2 weeks later
Rate of positive pregnancies over total transfers performed, according to beta-test result
3 secondary outcomes
Implantation rate
Time frame: up to 8 weeks of gestational age
Cancelation rate
Time frame: Perioperative/Periprocedural
Miscarriage rate
Time frame: From embryo transfer to delivery, up to 40 weeks
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 13 Jan 2026.
- Individual participant dataSharing planned: Yes. All IPD collected throughout the trial.
Related trials for Embryo Transfer
Not yet recruiting
Cryopreserved Pre-embryo Transfer in a Cytokine-rich Medium Versus Hyaluronic Acid
Frozen Embryo Transfer (FET)
Active, not recruitingPhase 3
Human Menopausal Gonadotropin Research in Infertility Assessing Cumulative Live Birth With Frozen Embryo Transfer.
Infertility (IVF Patients)
Not yet recruitingObservational study
Linzagolix in Adenomyosis and Recurrent Implantation Failure
Adenomyosis of Uterus, Implantation Failure
RecruitingPhase 2
Effect of FB301 on Vaginal Bacterial Profile in Women With Asymptomatic Vaginal Dysbiosis Undergoing a Mock Frozen Embryo Transfer Cycle
Vaginal Dysbiosis
RecruitingPhase 2/3
Thymosin-α1 for Recurrent Implantation Failure
Recurrent Implantation Faliure
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Trigger at smaller folicular size in people with Embryo Transfer, run by Vida Recoletas Sevilla at 1 site in Spain.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 2 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 13 Jan 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Spain. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Manuel Fernández Sánchez, MD PhD (+34954286274, vida.investiga@gruporecoletas.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Pregnancy rate (time frame: From embryo transfer up to 2 weeks later). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 13 Jan 2026.