Clinical PregnancyFETNCT05215119
Immediate Versus Delayed Natural Cycle Frozen Embryo Transfers
An observational study of Clinical Pregnancy, run by Antalya IVF at 1 site in Turkey (Türkiye).
Trial summary
Introduction: Based on recent studies the suggestion is that natural cycle frozen embryo transfers (NC FET) should preferably be used, with evidence suggesting that artificial cycle FET (AC FET) is subject to increased risks of adverse obstetric and perinatal outcomes and possibly lower live birth rates. Read more about this study
- Who is it for?
- Ages 18 to 40 yearsHealthy volunteers can take part
- Conditions the study is for
- Clinical Pregnancy
- What is being tested?
- natural cycle endometrial preparation
- Type of treatment
- Surgery or procedure
- How many people
- 818 participants
- Where
- 1 siteTurkey (Türkiye)
- Study dates
- 4 Mar 2022to 8 Feb 2025
- Phase
- Observational
- Are there results?
- None posted in the registry
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 40 years
- All sexes
- Healthy volunteers accepted
- Adult
Study population: Study participants will be recruited from (unselected) infertile patients presenting for freeze-all-IVF treatment at the IVF centre from the start date of enrollment.
Who may be able to join
- Patients with female age 18≤40 years.
- Patients who provide written informed consent to participate in the trial and for the use of their anonymized data in research.
- Patients with <2 previous IVF treatments.
- Patients with ≥1 blastocyst cryopreserved.
Who cannot join
- Patients with female age >40 years
- Patients with female BMI ≥30 kg/m2.
- Female patients with insulin dependent diabetes or non-insulin dependent diabetes mellitus and female patients with gastrointestinal, cardiovascular, pulmonary, liver or kidney disease.
- Female patients with any contraindications or allergies to the drugs used in routine freeze-all-IVF.
- Patients with untreated intrauterine anomalies and tubal pathology.
- Patients undergoing PGT-A (aneuploidy) or PGT-M (monogenic disorders)
- Patients with no blastocysts cryopreserved.
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Comparison of Immediate With Delayed Natural Cycle Frozen Embryo Transfers From Freeze-all-IVF Cycles: a Randomized Control Trial of First Frozen Embryo Transfers
Introduction:
Based on recent studies the suggestion is that natural cycle frozen embryo transfers (NC FET) should preferably be used, with evidence suggesting that artificial cycle FET (AC FET) is subject to increased risks of adverse obstetric and perinatal outcomes and possibly lower live birth rates. There, however, is limited evidence on the most efficient and effective timing of NC FET following oocyte retrieval.
Read more
Objective: In this non-inferiority randomised controlled trial, the effect on reproductive outcomes of NC FET performed immediately following the oocyte retrieval cycle (i.e., after one menstruation) will be investigated.
Materials and Methods: At a single IVF centre, patients will be recruited from infertile patients presenting for freeze-all-IVF treatments. Patients aged 18 to 30 years will be enrolled, if they had ≤2 previous embryo transfers and had ≥1 blastocyst cryopreserved in their freeze-all cycles. Enrolled patients (N = 800) will be randomised (1:1) to either the immediate group (i.e., FET performed in the menstrual cycle immediately following the oocyte retrieval cycle) or the delayed group (i.e., FET performed in the menstrual cycle following two menstruations). All FET will be performed in NC. The primary outcome measure will be clinical pregnancy, defined as the visual confirmation by transvaginal ultrasound scan of a gestational sac with normal heartbeat at >5 weeks of gestation. The analyses will be performed according to per-procedure principles.
Results: The ovarian, endometrial and time to transfer outcomes of the immediate group will be compared with those of the delayed group. The clinical pregnancy rate of the immediate group will be compared with that of the delayed group.
Read the detailed description
Introduction The increasing success of frozen embryo transfers (FET) in assisted reproductive technology (ART), and, therefore, the increasing use of FET to overcome standard IVF complications (i.e., adverse ovarian stimulation iatrogenesis and intra-cycle discovery of intrauterine abnormalities) and to facilitate the use of modified IVF treatment (i.e., pre-implantation genetic testing and luteal ovarian stimulation) has highlighted disadvantages inherent to FET. The major concern is the evidence that FET pregnancies are subject to adverse obstetric and perinatal outcomes such as placental and hypertensive complications, large for gestational age infants, increased pregnancy loss, increased preterm delivery. Moreover, the presumed benefits of more physiological endometria in FET demands further research into the origins of the adverse obstetric and perinatal outcomes and the elimination of their causes.
Endometrial preparation methods in FET can be divided into two major groups, artificial (AC) and natural cycle (NC) methods. While the initial studies comparing endometrial preparation methods for FET and confirmed by study reviews and meta-analyses, showed that no one method was superior in terms of reproductive outcomes, recent studies have shown that the NC cycle method results in reduced adverse obstetric and perinatal outcome rates and increased live birth rates. There is increasing evidence and understanding that using the AC method significantly increases the risks of adverse obstetric and perinatal outcomes because of the absence of a functional corpus luteum (CL). In addition to the production of hormones (i.e., estrogen and progesterone), CL also produces vasoactive molecules (i.e., relaxin, vascular endothelial growth factor) essential for optimal vascular developments in early pregnancy (i.e., implantation and placentation). Based on recent studies the suggestion, therefore, is that clinicians should preferably use NC FET. Further research, however, may be required to confirm the most optimal endometrial preparation and timing (i.e., embryo and endometrial synchrony) method for FET, because suggested preference is still being based on poor-quality evidence.
There is limited evidence on the most efficient and effective timing of NC FET following oocyte retrieval (i.e., the cycle subject to ovarian stimulation), as nearly all previous studies included the investigation of mostly AC FET. These studies, at most, confirmed that reproductive outcomes were not disadvantaged if FET were performed immediately following the oocyte retrieval cycle. Therefore, suggesting that ovarian stimulation (i.e., supraphysiological hormone levels) had no spill-over effects on endometrial and ovarian function in subsequent menstrual cycles, even in the cycle immediately following oocyte retrieval. Not having an extended delay to FET is considered by most patients to be less stressful and by clinicians to be more efficient. In this non-inferiority randomised controlled trial, the effect on reproductive outcomes of NC FET performed in menstrual cycles immediately following the oocyte retrieval cycle will be investigated.
- Conditions
- Clinical Pregnancy
- Being tested
- natural cycle endometrial preparation
- Keywords
- frozen embryo transfer, time-to-transfer, natural cycle, endometrial preparation
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
natural cycle endometrial preparationProcedure or surgery
Cycles will be monitored from either day-10 or-12, according to patient's menstrual cycle length, with serial analysis of blood serum LH and progesterone levels and assessment of dominant follicle growth. In a spontaneous cycle, ovulation will be determined by a LH surge (>20 IU/L) and a corresponding rise in progesterone (>0.8 ng/ml). In a triggered cycle, ovulation will be determined by the administration of an hCG trigger when the dominate follicle reached >16 mm (and LH was <20 IU/L).
| Study group | Role | What they receive |
|---|---|---|
| Immediate | NC endometrial preparation will start immediately after blastocyst cryopreservation confirmation. Receives: Procedure: natural cycle endometrial preparation | |
| Delayed | NC endometrial preparation will start on day 1 of the patient's 2nd menstruation after the oocyte retrieval cycle menstruation or in a subsequent cycle. Receives: Procedure: natural cycle endometrial preparation |
What is being measured
The primary outcome is the main question the study is designed to answer.
Clinical pregnancy from frozen embryo transfers
Clinical pregnancy rate will be defined as a pregnancy cycle with a normal gestational sac and fetal heartbeat confirmed by ultrasound at >5.5 weeks of gestation.
Measured: Transvaginal ultrasound examination will be performed after 5 weeks of gestation (>5.5 weeks)
Secondary outcomes (3)
Pregnancy from frozen embryo transfers
Pregnancy will be defined as a cycle with an arbitrary serum βHCG level of >5 mIU/mL, measured 9 days after blastocyst transfer.
Measured: Blood serum pregnancy tests will be performed 9 days after blastocyst transfer
Early pregnancy loss of frozen embryo transfer pregnancies
Early pregnancy loss will be defined as a pregnancy lost before 10 weeks of gestation.
Measured: Serial transvaginal ultrasound scans will be performed to 12 weeks of gestation
Ongoing pregnancy from frozen embryo transfers
Ongoing pregnancy will be defined as a clinical pregnancy developing normally past 12 weeks of gestation.
Measured: Transvaginal ultrasound scan will be performed after 12 weeks of gestation
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted31 Jan 2022
- Study start4 Mar 2022
- Primary completion8 Feb 2025
- Study completion8 Feb 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (8)Papers the sponsor has linked to this study.
- Other trials for Clinical PregnancyStudies 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
- Observational
- Observational model
- Case-control
- Time perspective
- Prospective
- Enrolment
- 818 participants (actual)
Sponsor and investigators
- Lead sponsor
- Antalya IVF
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05215119
- Sponsor's protocol ID
- timetoFETJan2022
- Acronym
- FET
- Status last verified
- Feb 2025
- First submitted
- 18 Jan 2022
- Last updated
- 11 Feb 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: The
Publications
Mackens S, Santos-Ribeiro S, van de Vijver A, Racca A, Van Landuyt L, Tournaye H, Blockeel C. Frozen embryo transfer: a review on the optimal endometrial preparation and timing. Hum Reprod. 2017 Nov 1;32(11):2234-2242. doi: 10.1093/humrep/dex285.
PubMed 29025055Groenewoud ER, Cantineau AE, Kollen BJ, Macklon NS, Cohlen BJ. What is the optimal means of preparing the endometrium in frozen-thawed embryo transfer cycles? A systematic review and meta-analysis. Hum Reprod Update. 2013 Sep-Oct;19(5):458-70. doi: 10.1093/humupd/dmt030. Epub 2013 Jul 2.
PubMed 23820515von Versen-Hoynck F, Narasimhan P, Selamet Tierney ES, Martinez N, Conrad KP, Baker VL, Winn VD. Absent or Excessive Corpus Luteum Number Is Associated With Altered Maternal Vascular Health in Early Pregnancy. Hypertension. 2019 Mar;73(3):680-690. doi: 10.1161/HYPERTENSIONAHA.118.12046.
PubMed 30636549Singh B, Reschke L, Segars J, Baker VL. Frozen-thawed embryo transfer: the potential importance of the corpus luteum in preventing obstetrical complications. Fertil Steril. 2020 Feb;113(2):252-257. doi: 10.1016/j.fertnstert.2019.12.007.
PubMed 32106972Makhijani R, Bartels C, Godiwala P, Bartolucci A, Nulsen J, Grow D, Benadiva C, Engmann L. Maternal and perinatal outcomes in programmed versus natural vitrified-warmed blastocyst transfer cycles. Reprod Biomed Online. 2020 Aug;41(2):300-308. doi: 10.1016/j.rbmo.2020.03.009. Epub 2020 Mar 21.
PubMed 32505542Pier BD, Havemann LM, Quaas AM, Heitmann RJ. Frozen-thawed embryo transfers: time to adopt a more "natural" approach? J Assist Reprod Genet. 2021 Aug;38(8):1909-1911. doi: 10.1007/s10815-021-02151-y. Epub 2021 Mar 19.
PubMed 33738681Wu H, Zhou P, Lin X, Wang S, Zhang S. Endometrial preparation for frozen-thawed embryo transfer cycles: a systematic review and network meta-analysis. J Assist Reprod Genet. 2021 Aug;38(8):1913-1926. doi: 10.1007/s10815-021-02125-0. Epub 2021 Apr 7.
PubMed 33829375Matorras R, Pijoan JI, Perez-Ruiz I, Lainz L, Malaina I, Borjaba S. Meta-analysis of the embryo freezing transfer interval. Reprod Med Biol. 2021 Jan 5;20(2):144-158. doi: 10.1002/rmb2.12363. eCollection 2021 Apr.
PubMed 33850447
Study at a glance
From the registry record, last updated by the sponsor on 11 Feb 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Comparison of Immediate With Delayed Natural Cycle Frozen Embryo Transfers From Freeze-all-IVF Cycles: a Randomized Control Trial of First Frozen Embryo Transfers
- ClinicalTrials.gov ID
- NCT05215119
- Acronym / sponsor ID
- FET / timetoFETJan2022
- Conditions
- Clinical Pregnancy
- Keywords
- frozen embryo transfer, time-to-transfer, natural cycle, endometrial preparation
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 818 participants (actual)
- Lead sponsor
- Antalya IVFUniversity, hospital or other
- Study start
- 4 Mar 2022 (actual)
- Primary completion
- 8 Feb 2025 (actual)
- Study completion
- 8 Feb 2025 (actual)
- First posted
- 31 Jan 2022 (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.
Introduction:
Based on recent studies the suggestion is that natural cycle frozen embryo transfers (NC FET) should preferably be used, with evidence suggesting that artificial cycle FET (AC FET) is subject to increased risks of adverse obstetric and perinatal outcomes and possibly lower live birth rates. There, however, is limited evidence on the most efficient and effective timing of NC FET following oocyte retrieval.
Objective: In this non-inferiority randomised controlled trial, the effect on reproductive outcomes of NC FET performed immediately following the oocyte retrieval cycle (i.e., after one menstruation) will be investigated.
Materials and Methods: At a single IVF centre, patients will be recruited from infertile patients presenting for freeze-all-IVF treatments. Patients aged 18 to 30 years will be enrolled, if they had ≤2 previous embryo transfers and had ≥1 blastocyst cryopreserved in their freeze-all cycles. Enrolled patients (N = 800) will be randomised (1:1) to either the immediate group (i.e., FET performed in the menstrual cycle immediately following the oocyte retrieval cycle) or the delayed group (i.e., FET performed in the menstrual cycle following two menstruations). All FET will be performed in NC. The primary outcome measure will be clinical pregnancy, defined as the visual confirmation by transvaginal ultrasound scan of a gestational sac with normal heartbeat at >5 weeks of gestation. The analyses will be performed according to per-procedure principles.
Results: The ovarian, endometrial and time to transfer outcomes of the immediate group will be compared with those of the delayed group. The clinical pregnancy rate of the immediate group will be compared with that of the delayed group.
Detailed description
Introduction The increasing success of frozen embryo transfers (FET) in assisted reproductive technology (ART), and, therefore, the increasing use of FET to overcome standard IVF complications (i.e., adverse ovarian stimulation iatrogenesis and intra-cycle discovery of intrauterine abnormalities) and to facilitate the use of modified IVF treatment (i.e., pre-implantation genetic testing and luteal ovarian stimulation) has highlighted disadvantages inherent to FET. The major concern is the evidence that FET pregnancies are subject to adverse obstetric and perinatal outcomes such as placental and hypertensive complications, large for gestational age infants, increased pregnancy loss, increased preterm delivery. Moreover, the presumed benefits of more physiological endometria in FET demands further research into the origins of the adverse obstetric and perinatal outcomes and the elimination of their causes.
Endometrial preparation methods in FET can be divided into two major groups, artificial (AC) and natural cycle (NC) methods. While the initial studies comparing endometrial preparation methods for FET and confirmed by study reviews and meta-analyses, showed that no one method was superior in terms of reproductive outcomes, recent studies have shown that the NC cycle method results in reduced adverse obstetric and perinatal outcome rates and increased live birth rates. There is increasing evidence and understanding that using the AC method significantly increases the risks of adverse obstetric and perinatal outcomes because of the absence of a functional corpus luteum (CL). In addition to the production of hormones (i.e., estrogen and progesterone), CL also produces vasoactive molecules (i.e., relaxin, vascular endothelial growth factor) essential for optimal vascular developments in early pregnancy (i.e., implantation and placentation). Based on recent studies the suggestion, therefore, is that clinicians should preferably use NC FET. Further research, however, may be required to confirm the most optimal endometrial preparation and timing (i.e., embryo and endometrial synchrony) method for FET, because suggested preference is still being based on poor-quality evidence.
There is limited evidence on the most efficient and effective timing of NC FET following oocyte retrieval (i.e., the cycle subject to ovarian stimulation), as nearly all previous studies included the investigation of mostly AC FET. These studies, at most, confirmed that reproductive outcomes were not disadvantaged if FET were performed immediately following the oocyte retrieval cycle. Therefore, suggesting that ovarian stimulation (i.e., supraphysiological hormone levels) had no spill-over effects on endometrial and ovarian function in subsequent menstrual cycles, even in the cycle immediately following oocyte retrieval. Not having an extended delay to FET is considered by most patients to be less stressful and by clinicians to be more efficient. In this non-inferiority randomised controlled trial, the effect on reproductive outcomes of NC FET performed in menstrual cycles immediately following the oocyte retrieval cycle will be investigated.
Study design
- Observational model
- Case-control
- Time perspective
- Prospective
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Immediate | – | Procedure: natural cycle endometrial preparationNC endometrial preparation will start immediately after blastocyst cryopreservation confirmation. |
| Delayed | – | Procedure: natural cycle endometrial preparationNC endometrial preparation will start on day 1 of the patient's 2nd menstruation after the oocyte retrieval cycle menstruation or in a subsequent cycle. |
Who may qualify
- Ages
- 18 to 40 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
- Study population
- Study participants will be recruited from (unselected) infertile patients presenting for freeze-all-IVF treatment at the IVF centre from the start date of enrollment.
Key inclusion criteria (4 listed)
- Patients with female age 18≤40 years.
- Patients who provide written informed consent to participate in the trial and for the use of their anonymized data in research.
- Patients with <2 previous IVF treatments.
- Patients with ≥1 blastocyst cryopreserved.
Key exclusion criteria (7 listed)
- Patients with female age >40 years
- Patients with female BMI ≥30 kg/m2.
- Female patients with insulin dependent diabetes or non-insulin dependent diabetes mellitus and female patients with gastrointestinal, cardiovascular, pulmonary, liver or kidney disease.
- Female patients with any contraindications or allergies to the drugs used in routine freeze-all-IVF.
- Patients with untreated intrauterine anomalies and tubal pathology.
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 |
|---|---|---|
| natural cycle endometrial preparationCycles will be monitored from either day-10 or-12, according to patient's menstrual cycle length, with serial analysis of blood serum LH and progesterone levels and assessment of dominant follicle growth. In a spontaneous cycle, ovulation will be determined by a LH surge (>20 IU/L) and a corresponding rise in progesterone (>0.8 ng/ml). In a triggered cycle, ovulation will be determined by the administration of an hCG trigger when the dominate follicle reached >16 mm (and LH was <20 IU/L). | Procedure or surgery | Delayed, Immediate |
Primary outcome
Clinical pregnancy from frozen embryo transfers
Time frame: Transvaginal ultrasound examination will be performed after 5 weeks of gestation (>5.5 weeks)
Clinical pregnancy rate will be defined as a pregnancy cycle with a normal gestational sac and fetal heartbeat confirmed by ultrasound at >5.5 weeks of gestation.
3 secondary outcomes
Pregnancy from frozen embryo transfers
Time frame: Blood serum pregnancy tests will be performed 9 days after blastocyst transfer
Early pregnancy loss of frozen embryo transfer pregnancies
Time frame: Serial transvaginal ultrasound scans will be performed to 12 weeks of gestation
Ongoing pregnancy from frozen embryo transfers
Time frame: Transvaginal ultrasound scan will be performed after 12 weeks of gestation
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 11 Feb 2025.
- Results publication: PubMed 29025055Mackens S, Santos-Ribeiro S, van de Vijver A, Racca A, Van Landuyt L, Tournaye H, Blockeel C. Frozen embryo transfer: a review on the optimal endometrial preparation and timing. Hum Reprod. 2017 Nov 1;32(11):2234-2242. doi: 10.1093/humrep/dex285.
- Results publication: PubMed 23820515Groenewoud ER, Cantineau AE, Kollen BJ, Macklon NS, Cohlen BJ. What is the optimal means of preparing the endometrium in frozen-thawed embryo transfer cycles? A systematic review and meta-analysis. Hum Reprod Update. 2013 Sep-Oct;19(5):458-70. doi: 10.1093/humupd/dmt030. Epub 2013 Jul 2.
- Results publication: PubMed 30636549von Versen-Hoynck F, Narasimhan P, Selamet Tierney ES, Martinez N, Conrad KP, Baker VL, Winn VD. Absent or Excessive Corpus Luteum Number Is Associated With Altered Maternal Vascular Health in Early Pregnancy. Hypertension. 2019 Mar;73(3):680-690. doi: 10.1161/HYPERTENSIONAHA.118.12046.
- Results publication: PubMed 32106972Singh B, Reschke L, Segars J, Baker VL. Frozen-thawed embryo transfer: the potential importance of the corpus luteum in preventing obstetrical complications. Fertil Steril. 2020 Feb;113(2):252-257. doi: 10.1016/j.fertnstert.2019.12.007.
- Results publication: PubMed 32505542Makhijani R, Bartels C, Godiwala P, Bartolucci A, Nulsen J, Grow D, Benadiva C, Engmann L. Maternal and perinatal outcomes in programmed versus natural vitrified-warmed blastocyst transfer cycles. Reprod Biomed Online. 2020 Aug;41(2):300-308. doi: 10.1016/j.rbmo.2020.03.009. Epub 2020 Mar 21.
- Results publication: PubMed 33738681Pier BD, Havemann LM, Quaas AM, Heitmann RJ. Frozen-thawed embryo transfers: time to adopt a more "natural" approach? J Assist Reprod Genet. 2021 Aug;38(8):1909-1911. doi: 10.1007/s10815-021-02151-y. Epub 2021 Mar 19.
- Results publication: PubMed 33829375Wu H, Zhou P, Lin X, Wang S, Zhang S. Endometrial preparation for frozen-thawed embryo transfer cycles: a systematic review and network meta-analysis. J Assist Reprod Genet. 2021 Aug;38(8):1913-1926. doi: 10.1007/s10815-021-02125-0. Epub 2021 Apr 7.
- Results publication: PubMed 33850447Matorras R, Pijoan JI, Perez-Ruiz I, Lainz L, Malaina I, Borjaba S. Meta-analysis of the embryo freezing transfer interval. Reprod Med Biol. 2021 Jan 5;20(2):144-158. doi: 10.1002/rmb2.12363. eCollection 2021 Apr.
- Individual participant dataSharing planned: Yes. The
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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. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Clinical Pregnancy, run by Antalya IVF at 1 site in Turkey (Türkiye).
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 4 inclusion and 7 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: finished, as of the sponsor's last update on 11 Feb 2025. 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 Turkey (Türkiye). 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?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Clinical pregnancy from frozen embryo transfers (time frame: Transvaginal ultrasound examination will be performed after 5 weeks of gestation (>5.5 weeks)). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT05215119, which also lists 8 linked publications.
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 11 Feb 2025; AzTrials last refreshed its copy on 6 Nov 2026.