InfertilityFRESH-FROZENNCT07904936
Fresh Versus Vitrified-Warmed Donor Oocytes: Embryological and Clinical Outcomes
An observational study of Infertility and Donor Oocyte Assisted Reproduction, run by Center for Reproductive Medicine Bocian at 1 site in Poland.
Trial summary
This multicenter retrospective observational study compares embryological and clinical outcomes following treatment with fresh versus vitrified-warmed donor oocytes at Bocian Fertility Clinic centers in Poland. Read more about this study
- Who is it for?
- Ages 18 years and older, women only
- Conditions the study is for
- Infertility, Donor Oocyte Assisted Reproduction
- What is being tested?
- Fresh Donor Oocyte ICSI and Vitrified-Warmed Donor Oocyte ICSI
- Type of treatment
- Injection or infusion, Surgery or procedure
- How many people
- 3,000 participants
- Where
- 1 sitePoland
- Study dates
- 1 Mar 2026to Jun 2028
- Phase
- Observational
- 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 years and older
- Women only
- No healthy volunteers
- Adult, Older adult
Study population: The study population comprises adult female recipients undergoing assisted reproductive treatment with fresh or vitrified-warmed donor oocytes at Bocian Fertility Clinic centers in Poland. Participants will be identified retrospectively from routinely collected clinical and embryology databases. The principal analytical cohort includes recipient treatment cycles with an identifiable initial allocation of six mature donor oocytes. Outcomes will be evaluated from the initial allocation, irrespective of subsequent fertilization, embryo development, or embryo transfer.
Who may be able to join
- Female recipients aged 18 years or older undergoing assisted reproductive treatment using donor oocytes at participating Bocian Fertility Clinic centers in Poland.
- Treatment cycles initiated within the prespecified historical study period, with the last eligible cycle occurring on September 30, 2026.
- Recipient cycles involving fresh or vitrified-warmed donor oocytes mature at the metaphase II (MII) stage.
- An identifiable initial allocation of six mature donor oocytes intended for ICSI, before any warming-related losses.
- Availability of laboratory records allowing identification of the donor-oocyte strategy and linkage to the recipient treatment cycle.
- Cycles without fertilization, usable embryos, or embryo transfer remain eligible.
Who cannot join
- Treatment cycles using autologous rather than donor oocytes.
- Cycles involving embryo donation without an identifiable recipient-specific donor-oocyte allocation.
- Mixed fresh and vitrified-warmed oocyte allocations within the same index treatment cycle.
- Cycles with no verifiable initial six-MII allocation or insufficient information to classify the oocyte strategy.
- Duplicate records referring to the same index oocyte allocation.
Trial locations and contacts
1 site in 1 country.
Poland1 site
Bocian Fertility Clinic
Szczecin, West Pomeranian Voivodeship, 70-255
About this study
Official title: From Six Allocated Mature Donor Oocytes to Live Birth: A Multicenter Retrospective Cohort Study Comparing Fresh and Vitrified-Warmed Oocyte Donation Strategies
This multicenter retrospective observational study compares embryological and clinical outcomes following treatment with fresh versus vitrified-warmed donor oocytes at Bocian Fertility Clinic centers in Poland. The study focuses on a standardized allocation strategy in which recipients are intended to receive six mature (metaphase II, MII) donor oocytes. In the vitrified-warmed group, oocytes are cryopreserved at the MII stage and subsequently warmed for use. Oocytes lost during warming are not routinely replaced, allowing the study to evaluate the consequences of warming-related losses within the initial allocation. The study will assess fertilization, embryo development, usable blastocyst yield, the probability of obtaining an embryo for transfer, and live birth following the first embryo transfer originating from the allocated oocytes. Clinical effectiveness will be evaluated from the initial oocyte allocation, including cycles in which no embryo transfer occurs. The objective is to determine whether fresh and vitrified-warmed donor-oocyte strategies are associated with differences in embryological efficiency and the likelihood of live birth when the initial number of mature allocated oocytes is standardized.
Read the detailed description
Background and rationale Fresh and vitrified-warmed donor oocytes are widely used in assisted reproductive technology. Although modern vitrification has substantially improved oocyte survival, comparisons between fresh and warmed oocytes may be complicated by differences in the number of oocytes allocated to recipients and by the use of outcome measures restricted to cycles reaching embryo transfer. This study examines the entire reproductive pathway beginning with a standardized initial allocation of six mature donor oocytes. The approach allows the assessment of both quantitative losses associated with warming and subsequent embryological and clinical outcomes.
Study design and population This is a multicenter, retrospective, observational cohort study using routinely collected clinical and laboratory data from Bocian Fertility Clinic centers in Poland. Eligible donor-oocyte treatment cycles occurring up to September 30, 2026, will be evaluated. Two groups will be compared: recipients treated with fresh donor oocytes and recipients treated with vitrified-warmed donor oocytes.
Oocyte allocation and laboratory assessment Under the standard program, six mature donor oocytes are allocated to a recipient. In the fresh strategy, six mature oocytes are made available for intracytoplasmic sperm injection (ICSI). In the vitrified-warmed strategy, donor oocytes are vitrified at the MII stage, generally stored in groups of three per carrier, and warmed for treatment. Losses during warming are not routinely compensated for by warming additional oocytes. The study will examine the number of oocytes available for ICSI, normally fertilized oocytes (2PN), embryo development, blastocyst formation, and the number of usable blastocysts. Outcomes will be expressed using both the initial allocation and relevant stage-specific denominators.
Clinical outcomes The primary clinical outcome will be live birth following the first embryo transfer derived from the initial oocyte allocation, expressed per recipient allocation. Cycles without embryo transfer will remain in the initial cohort denominator. Live birth per performed first embryo transfer will be evaluated separately.
Where sufficiently complete follow-up is available, cumulative live birth outcomes arising from embryos obtained from the same initial allocation may also be examined.
Analysis Associations between oocyte strategy and reproductive outcomes will be assessed while considering relevant donor, recipient, paternal, calendar-period, and center characteristics. Repeated contributions from the same oocyte donor will be accounted for where linkage data permit.
The study is observational and does not alter routine treatment, oocyte allocation, vitrification, warming, fertilization, embryo culture, or embryo transfer procedures.
- Conditions
- Infertility, Donor Oocyte Assisted Reproduction
- Being tested
- Fresh Donor Oocyte ICSI, Vitrified-Warmed Donor Oocyte ICSI
- Keywords
- Oocyte donation, Fresh donor oocytes, Oocyte vitrification, Vitrified-warmed donor oocytes, Oocyte allocation, Intracytoplasmic sperm injection, Blastocyst development, Live birth
- Medical subject headings
- Infertility
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Fresh Donor Oocyte ICSIProcedure or surgery
Recipients underwent routine ICSI using fresh mature donor oocytes. Under the standard allocation strategy, six MII oocytes were allocated to each recipient. No treatment procedures were assigned or modified for research purposes.
Vitrified-Warmed Donor Oocyte ICSIProcedure or surgery
Recipients underwent routine ICSI using donor oocytes previously vitrified at the MII stage. Six vitrified MII oocytes were allocated for warming. Oocytes lost during warming were not routinely replaced. No treatment procedures were assigned or modified for research purposes.
| Study group | Role | What they receive |
|---|---|---|
| Fresh Donor Oocytes | Recipients undergoing assisted reproduction using fresh mature (metaphase II, MII) donor oocytes. Under the standard allocation strategy, six fresh MII oocytes are allocated to each recipient and made available for intracytoplasmic sperm injection (ICSI). Embryological and clinical outcomes are evaluated from the initial oocyte allocation, including cycles without embryo transfer. Receives: Procedure: Fresh Donor Oocyte ICSI | |
| Vitrified-Warmed Donor Oocytes | Recipients undergoing assisted reproduction using donor oocytes vitrified at the mature (metaphase II, MII) stage. Under the standard allocation strategy, six vitrified MII oocytes, typically stored on two carriers containing three oocytes each, are allocated and warmed for treatment. Oocytes that do not survive warming are not routinely replaced with additional oocytes. Embryological and clinical outcomes are evaluated from the initial allocation of six MII oocytes, including warming-related losses and cycles without embryo transfer. Receives: Procedure: Vitrified-Warmed Donor Oocyte ICSI |
What is being measured
The primary outcome is the main question the study is designed to answer.
Live Birth Following the First Embryo Transfer per Initial Donor-Oocyte Allocation
Proportion of eligible recipient allocations resulting in at least one live-born infant following the first embryo transfer derived from the initial donor-oocyte allocation. The denominator includes all eligible allocations of six mature (MII) donor oocytes, including those resulting in no transferable embryo or no embryo transfer. Each allocation contributes a maximum of one successful outcome. Allocations without a first transfer or with unresolved birth outcomes at the data cutoff will be identified and handled according to the prespecified analysis plan.
Measured: From initial donor-oocyte allocation through the pregnancy outcome of the first embryo transfer, assessed up to December 2027.
Secondary outcomes (6)
Mature Oocyte Availability for ICSI per Initial Allocation
Number of mature donor oocytes available for ICSI relative to the initial allocation of six MII oocytes. The measure captures quantitative loss before insemination and is compared between fresh and vitrified-warmed cohorts.
Measured: From initial allocation to ICSI (Day 0).
Normal Fertilization Rate
Proportion of injected MII oocytes exhibiting normal fertilization (2PN). Calculated per oocyte injected by ICSI, with the number of 2PN embryos per initial allocation also assessed.
Measured: Approximately 16-20 hours after ICSI (Day 1).
Usable Blastocyst Yield per Initial Oocyte Allocation
Number of usable blastocysts obtained from the initial donor-oocyte allocation, including allocations producing zero usable blastocysts. Usability is determined according to the participating laboratory's clinical criteria for transfer or cryopreservation.
Measured: Within 5-7 days after ICSI.
Availability of at Least One Usable Blastocyst
Proportion of initial donor-oocyte allocations producing at least one usable blastocyst suitable for embryo transfer or cryopreservation. All eligible allocations remain in the denominator.
Measured: Within 5-7 days after ICSI.
First Embryo Transfer Opportunity
Proportion of eligible initial donor-oocyte allocations resulting in at least one embryo transfer derived from the allocated oocytes within the prespecified follow-up period. Allocations without a transfer are retained in the denominator.
Measured: From initial allocation through December 2027.
Cumulative Live Birth per Initial Oocyte Allocation
Proportion of eligible initial donor-oocyte allocations resulting in at least one live birth from any embryo transfer derived from that allocation within the prespecified follow-up period. Assessed in a cohort with sufficiently complete follow-up; allocations with unresolved outcomes will be identified and addressed in the analysis.
Measured: From initial allocation through June 2028.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted29 Oct 2026
- Study start1 Mar 2026
- Primary completion30 Dec 2027 (estimated)
- Study completionJun 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for InfertilityStudies 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
- Cohort
- Time perspective
- Retrospective
- Enrolment
- 3,000 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Center for Reproductive Medicine Bocian
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Przemysław Ciepiela, Principal investigator, Bocian Fertility Clinic
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07904936
- Sponsor's protocol ID
- FRESH-FROZEN-OD-01
- Acronym
- FRESH-FROZEN
- Status last verified
- Oct 2026
- First submitted
- 23 Oct 2026
- Last updated
- 29 Oct 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: Individual participant data will not be publicly shared because the study uses retrospective clinical and laboratory records containing sensitive reproductive health information. Data access is subject to patient confidentiality, institutional policies, and applicable data protection regulations. Aggregated results will be reported in scientific publications.
Study at a glance
From the registry record, last updated by the sponsor on 29 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- From Six Allocated Mature Donor Oocytes to Live Birth: A Multicenter Retrospective Cohort Study Comparing Fresh and Vitrified-Warmed Oocyte Donation Strategies
- ClinicalTrials.gov ID
- NCT07904936
- Acronym / sponsor ID
- FRESH-FROZEN / FRESH-FROZEN-OD-01
- Conditions
- Infertility, Donor Oocyte Assisted Reproduction
- Keywords
- Oocyte donation, Fresh donor oocytes, Oocyte vitrification, Vitrified-warmed donor oocytes, Oocyte allocation, Intracytoplasmic sperm injection, Blastocyst development, Live birth
- Study type
- Observational
- Recruitment status
- Active, not recruiting
- Enrolment
- 3,000 participants (estimated)
- Lead sponsor
- Center for Reproductive Medicine BocianUniversity, hospital or other
- Study start
- 1 Mar 2026 (actual)
- Primary completion
- 30 Dec 2027 (estimated)
- Study completion
- Jun 2028 (estimated)
- First posted
- 29 Oct 2026 (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.
This multicenter retrospective observational study compares embryological and clinical outcomes following treatment with fresh versus vitrified-warmed donor oocytes at Bocian Fertility Clinic centers in Poland. The study focuses on a standardized allocation strategy in which recipients are intended to receive six mature (metaphase II, MII) donor oocytes. In the vitrified-warmed group, oocytes are cryopreserved at the MII stage and subsequently warmed for use. Oocytes lost during warming are not routinely replaced, allowing the study to evaluate the consequences of warming-related losses within the initial allocation. The study will assess fertilization, embryo development, usable blastocyst yield, the probability of obtaining an embryo for transfer, and live birth following the first embryo transfer originating from the allocated oocytes. Clinical effectiveness will be evaluated from the initial oocyte allocation, including cycles in which no embryo transfer occurs. The objective is to determine whether fresh and vitrified-warmed donor-oocyte strategies are associated with differences in embryological efficiency and the likelihood of live birth when the initial number of mature allocated oocytes is standardized.
Detailed description
Background and rationale Fresh and vitrified-warmed donor oocytes are widely used in assisted reproductive technology. Although modern vitrification has substantially improved oocyte survival, comparisons between fresh and warmed oocytes may be complicated by differences in the number of oocytes allocated to recipients and by the use of outcome measures restricted to cycles reaching embryo transfer. This study examines the entire reproductive pathway beginning with a standardized initial allocation of six mature donor oocytes. The approach allows the assessment of both quantitative losses associated with warming and subsequent embryological and clinical outcomes.
Study design and population This is a multicenter, retrospective, observational cohort study using routinely collected clinical and laboratory data from Bocian Fertility Clinic centers in Poland. Eligible donor-oocyte treatment cycles occurring up to September 30, 2026, will be evaluated. Two groups will be compared: recipients treated with fresh donor oocytes and recipients treated with vitrified-warmed donor oocytes.
Oocyte allocation and laboratory assessment Under the standard program, six mature donor oocytes are allocated to a recipient. In the fresh strategy, six mature oocytes are made available for intracytoplasmic sperm injection (ICSI). In the vitrified-warmed strategy, donor oocytes are vitrified at the MII stage, generally stored in groups of three per carrier, and warmed for treatment. Losses during warming are not routinely compensated for by warming additional oocytes. The study will examine the number of oocytes available for ICSI, normally fertilized oocytes (2PN), embryo development, blastocyst formation, and the number of usable blastocysts. Outcomes will be expressed using both the initial allocation and relevant stage-specific denominators.
Clinical outcomes The primary clinical outcome will be live birth following the first embryo transfer derived from the initial oocyte allocation, expressed per recipient allocation. Cycles without embryo transfer will remain in the initial cohort denominator. Live birth per performed first embryo transfer will be evaluated separately.
Where sufficiently complete follow-up is available, cumulative live birth outcomes arising from embryos obtained from the same initial allocation may also be examined.
Analysis Associations between oocyte strategy and reproductive outcomes will be assessed while considering relevant donor, recipient, paternal, calendar-period, and center characteristics. Repeated contributions from the same oocyte donor will be accounted for where linkage data permit.
The study is observational and does not alter routine treatment, oocyte allocation, vitrification, warming, fertilization, embryo culture, or embryo transfer procedures.
Study design
- Observational model
- Cohort
- Time perspective
- Retrospective
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Fresh Donor Oocytes | – | Procedure: Fresh Donor Oocyte ICSIRecipients undergoing assisted reproduction using fresh mature (metaphase II, MII) donor oocytes. Under the standard allocation strategy, six fresh MII oocytes are allocated to each recipient and made available for intracytoplasmic sperm injection (ICSI). Embryological and clinical outcomes are evaluated from the initial oocyte allocation, including cycles without embryo transfer. |
| Vitrified-Warmed Donor Oocytes | – | Procedure: Vitrified-Warmed Donor Oocyte ICSIRecipients undergoing assisted reproduction using donor oocytes vitrified at the mature (metaphase II, MII) stage. Under the standard allocation strategy, six vitrified MII oocytes, typically stored on two carriers containing three oocytes each, are allocated and warmed for treatment. Oocytes that do not survive warming are not routinely replaced with additional oocytes. Embryological and clinical outcomes are evaluated from the initial allocation of six MII oocytes, including warming-related losses and cycles without embryo transfer. |
Who may qualify
- Ages
- 18 years and older
- Sex
- Female only
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- The study population comprises adult female recipients undergoing assisted reproductive treatment with fresh or vitrified-warmed donor oocytes at Bocian Fertility Clinic centers in Poland. Participants will be identified retrospectively from routinely collected clinical and embryology databases. The principal analytical cohort includes recipient treatment cycles with an identifiable initial allocation of six mature donor oocytes. Outcomes will be evaluated from the initial allocation, irrespective of subsequent fertilization, embryo development, or embryo transfer.
Key inclusion criteria (6 listed)
- Female recipients aged 18 years or older undergoing assisted reproductive treatment using donor oocytes at participating Bocian Fertility Clinic centers in Poland.
- Treatment cycles initiated within the prespecified historical study period, with the last eligible cycle occurring on September 30, 2026.
- Recipient cycles involving fresh or vitrified-warmed donor oocytes mature at the metaphase II (MII) stage.
- An identifiable initial allocation of six mature donor oocytes intended for ICSI, before any warming-related losses.
- Availability of laboratory records allowing identification of the donor-oocyte strategy and linkage to the recipient treatment cycle.
Key exclusion criteria (5 listed)
- Treatment cycles using autologous rather than donor oocytes.
- Cycles involving embryo donation without an identifiable recipient-specific donor-oocyte allocation.
- Mixed fresh and vitrified-warmed oocyte allocations within the same index treatment cycle.
- Cycles with no verifiable initial six-MII allocation or insufficient information to classify the oocyte strategy.
- Duplicate records referring to the same index oocyte allocation.
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 |
|---|---|---|
| Fresh Donor Oocyte ICSIRecipients underwent routine ICSI using fresh mature donor oocytes. Under the standard allocation strategy, six MII oocytes were allocated to each recipient. No treatment procedures were assigned or modified for research purposes. | Procedure or surgery | Fresh Donor Oocytes |
| Vitrified-Warmed Donor Oocyte ICSIRecipients underwent routine ICSI using donor oocytes previously vitrified at the MII stage. Six vitrified MII oocytes were allocated for warming. Oocytes lost during warming were not routinely replaced. No treatment procedures were assigned or modified for research purposes. | Procedure or surgery | Vitrified-Warmed Donor Oocytes |
Primary outcome
Live Birth Following the First Embryo Transfer per Initial Donor-Oocyte Allocation
Time frame: From initial donor-oocyte allocation through the pregnancy outcome of the first embryo transfer, assessed up to December 2027.
Proportion of eligible recipient allocations resulting in at least one live-born infant following the first embryo transfer derived from the initial donor-oocyte allocation. The denominator includes all eligible allocations of six mature (MII) donor oocytes, including those resulting in no transferable embryo or no embryo transfer. Each allocation contributes a maximum of one successful outcome. Allocations without a first transfer or with unresolved birth outcomes at the data cutoff will be identified and handled according to the prespecified analysis plan.
6 secondary outcomes
Mature Oocyte Availability for ICSI per Initial Allocation
Time frame: From initial allocation to ICSI (Day 0).
Normal Fertilization Rate
Time frame: Approximately 16-20 hours after ICSI (Day 1).
Usable Blastocyst Yield per Initial Oocyte Allocation
Time frame: Within 5-7 days after ICSI.
Availability of at Least One Usable Blastocyst
Time frame: Within 5-7 days after ICSI.
First Embryo Transfer Opportunity
Time frame: From initial allocation through December 2027.
Cumulative Live Birth per Initial Oocyte Allocation
Time frame: From initial allocation through June 2028.
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 29 Oct 2026.
- Individual participant dataSharing planned: No. Individual participant data will not be publicly shared because the study uses retrospective clinical and laboratory records containing sensitive reproductive health information. Data access is subject to patient confidentiality, institutional policies, and applicable data protection regulations. Aggregated results will be reported in scientific publications.
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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.
Przemysław Ciepiela principal investigator
Bocian Fertility Clinic
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 Infertility and Donor Oocyte Assisted Reproduction, run by Center for Reproductive Medicine Bocian at 1 site in Poland.
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 6 inclusion and 5 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: under way, not looking for participants, as of the sponsor's last update on 29 Oct 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 Poland. 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?
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?
Live Birth Following the First Embryo Transfer per Initial Donor-Oocyte Allocation (time frame: From initial donor-oocyte allocation through the pregnancy outcome of the first embryo transfer, assessed up to December 2027.). 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 29 Oct 2026.