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Clinical trial Recruiting at 1 site Phase 3 Interventional Ages 18 to 44 Women only

Day‑3 (cleavage) versus day‑5–7 (blastocyst) embryo transfer for IVF patients with few embryos

Official title: Day 3 Versus Day 5 Embryo Transfer in IVF Patients With Few Embryos

Run by Beth Israel Deaconess Medical Center · NCT06746129 · Data updated 2026-11-12

This test compares whether transferring embryos on day 3 (8‑cell cleavage stage) or waiting until day 5–7 (blastocyst) leads to better pregnancy and live birth outcomes for people having their first IVF cycle who produce five or fewer embryos.

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Quick facts

PhasePhase 3
Study typeInterventional
Ages18 Years to 44 Years
SexWomen only
Enrollment1126 (estimated)
SponsorBeth Israel Deaconess Medical Center
Academic / other
Locations1 site (Boston, Massachusetts)
StatusRecruiting
StartedSeptember 10, 2025
Main results expectedDecember 2030
Study endsJune 30, 2031
Registry record updatedApril 2, 2026
Trial IDNCT06746129 on ClinicalTrials.gov

Is this trial a fit for you?

Likely a good fit

Ideal candidates are people aged 18–44 having their first autologous IVF cycle with ≤5 zygotes on day 1 who plan a fresh embryo transfer and do not meet exclusion criteria like planned PGT or uterine factor infertility.

Probably not a fit

Patients who have more than five embryos, plan universal preimplantation genetic testing, use a gestational carrier, have significant uterine factors, or who convert to an all‑freeze cycle are unlikely to benefit from this trial.

A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.

What this trial studies

This randomized Phase 3 trial will enroll about 1,126 people aged 18–44 undergoing their first autologous IVF cycle who have five or fewer embryos. Participants are randomly assigned to receive a fresh embryo transfer either at the cleavage stage (day 3) or after culture to blastocyst stage (day 5–7). Any surplus embryos that meet freezing criteria may be cryopreserved and used in later thaw cycles according to standard practice. Investigators will follow patients to compare pregnancy and live birth outcomes between the two timing strategies across multiple U.S. IVF centers.

Why it matters

Potential benefit: If successful, the results could help clinicians choose the transfer timing that maximizes live birth chances and minimizes unnecessary multiple pregnancies for patients with few embryos.

How similar studies have gone: Observational and prior trials suggest advantages to blastocyst transfer in broader IVF populations, but randomized evidence specifically for patients with few embryos is limited, making this question relatively untested in that subgroup.

Who can join: the full rules

Show full inclusion / exclusion criteria 
Inclusion Criteria:

* autologous IVF cycle
* ≤5 zygotes on day 1 of development
* Fresh embryo transfer

Exclusion Criteria:

* Planned preimplantation genetic testing (PGT) of all embryos
* More than 2 previous IVF cycles
* History of recurrent pregnancy loss (≥3)
* Body mass index \>40
* Presence of uterine factor infertility
* Planned gestational carrier
* Endometrial lining \<6mm measured on the day of trigger
* Lupron-only trigger, elevated progesterone in the fresh cycle (≥1.5ng/ml)
* Delayed fertilization (\>18 hours)
* Rescue intracytoplasmic sperm injection (following failed regular fertilization)
* Use of non-ejaculated sperm (testicular sperm extraction)
* Embryo transfer number outside American Society of Reproductive Medicine (ASRM) guidelines
* Cycle is converted to a cycle in which all embryos are frozen

Where it's running

  • Boston IVF
    Boston, Massachusetts, United States     Recruiting

Study contacts

  • Principal investigator: Werner Neuhausser, MD PhD — Beth Israel Deaconess Medical Center/Harvard Medical School
  • Study coordinator: Beatrice Duvert
  • Email: bduvert@bidmc.harvard.edu
  • Phone: 617-975-7632

Similar studies

Other studies for the same condition or treatment. Recruiting studies are listed first.

How to take part

  1. Review the eligibility criteria above with your treating physician.
  2. Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
  3. Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.
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Infertility (IVF Patients) 23Beth Israel Deaconess Medical Center 577
Last reviewed 2026-11-14 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.