Comparing immediate and postponed embryo transfer for infertility treatment

Immediate Versus Postponed Single Blastocyst Transfer in Programmed or Stimulated Cycle Frozen Embryo Transfer: a Multicenter Randomized Controlled Trial

Not applicable Interventional Rigshospitalet, Denmark · NCT06304792

This study is testing whether transferring an embryo right after egg retrieval is just as effective as waiting to transfer it later for helping people with infertility have a baby.

Quick facts

PhaseNot applicable
Study typeInterventional
Enrollment484 (estimated)
Ages18 Years to 40 Years
SexFemale
SponsorRigshospitalet, Denmark Academic / other
Locations1 site (Copenhagen)
Trial IDNCT06304792 on ClinicalTrials.gov

What this trial studies

This randomized controlled trial aims to determine if immediate single blastocyst transfer after oocyte retrieval is as effective as postponed transfer in achieving live births. The study will include 484 patients who will be randomly assigned to either immediate or postponed frozen embryo transfer (FET) in a multicenter setting. Participants will undergo assessments and treatments based on their randomization, with the primary outcome being the live birth rate. The trial is set to run from February 2024 to August 2028.

Who should consider this trial

Good fit: Ideal candidates include women eligible for frozen embryo transfer following a fresh embryo transfer or freeze-all cycle, including both ovulatory and oligo-anovulatory women.

Not a fit: Patients with uterine malformations, severe reproductive health issues, or those requiring oocyte donation may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could provide insights into optimizing embryo transfer timing, potentially improving live birth rates for patients undergoing IVF.

How similar studies have performed: Other studies have explored embryo transfer timing, but this specific comparison of immediate versus postponed transfer is relatively novel.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* Eligible for FET in a programmed- or stimulated cycle immediately following a fresh embryo transfer or freeze all cycle
* Oligo-anovulatory women (cycle length \> 35 days)
* Ovulatory women (cycle length 21-35 days)
* At least one vitrified day 5 or 6 blastocyst with Gardner score of ≥ 3BB at the day of vitrification

Exclusion Criteria:

* Uterine malformation
* Presence of hydrosalpinx, submucosal uterine myomas or uterine polyps
* Allergies or contraindication to standard fertility medication
* Male or female HIV or Hepatitis B or C
* Preimplantation genetic testing (PGT) in the fresh cycle
* Testicular sperm aspiration (TESA)
* Severe OHSS with hospital admission and ascites drainage during the fresh cycle
* Oocyte donation

Where this trial is running

Copenhagen

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions InfertilityIVF
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.