for females ages 18-42 (full criteria)
at San Francisco, California and other locations
study started
estimated completion
Marcelle I Cedars, MD



The trial objective is to determine whether the deferred transfer of embryos following cryopreservation at the blastocyst stage following pre-implantation genetic screening (PGS-FET) improves live birthrates compared to both the deferred transfer of cryopreserved embryos without PGS (FET) and immediate transfer at the conclusion of a "fresh" in vitro fertilization (IVF) cycle (Fresh). Additionally, whether "freeze-only" (FET) improves live birth rates compared to "fresh" will be determined.

Official Title

A Prospective, Randomized, Controlled Clinical Trial Evaluating the Superiority of Preimplantation Genetic Screening (PGS) and Deferred Transfer of Cryopreserved Embryos Over "Freeze-Only" Deferred Transfer Without PGS or Immediate Embryo Transfer During a "Fresh" In Vitro Fertilization Cycle


This will be a multi-center, prospective randomized clinical trial comparing three standards of care:

Group 1: PGS-FET group: deferred transfer of day 5/6/7 (blastocyst stage) embryos cryopreserved following trophectoderm biopsy Group 2: "freeze-only" (FET) group: deferred transfer of frozen/thawed embryos without biopsy Group 3: "fresh" ET group: immediate transfer of "fresh" embryos in the stimulation cycle.

1539 eligible couples will be recruited to participate. Couples will be randomized at retrieval to undergo cryopreservation with deferred embryo transfer, with or without PGS, or fresh embryo transfer during the cycle of egg retrieval. Number of embryos to transfer will be based on clinical estimation of embryo quality and will not exceed ASRM guidelines for embryo transfer number including newly revised guidelines. We are aware that the number of embryos transferred, to maintain enrollment, may not be equivalent, with likely more embryos transferred in patients not having PGS. The primary outcome of live birth/retrieval, with a secondary outcome of healthy singleton birth, may reflect the true benefit of PGS.


Infertility Trophectoderm biopsy Cryopreservation Embryo Transfer PGS-FET FET Fresh


You can join if…

Open to females ages 18-42

  • Scheduled to undergo in vitro fertilization for treatment of infertility (1st or 2nd "fresh" attempt); subject can have had no more than one prior failed "fresh" IVF cycle
  • Couple able to participate in a research project
  • Able to understand study requirements
  • Willing to sign informed consent
  • Able to return for required follow-up
  • Access to telephone
  • Ability to read and write
  • Normal uterine cavity evaluation within one year of enrollment

You CAN'T join if...

  • Medical conditions which may complicate treatment
  • No plans to undergo embryo transfer
  • Medical contraindication to the transfer of more than a single embryo (i.e. congenital uterine anomaly).
  • Concurrent participation in any other interventional trial
  • Recurrent pregnancy loss
  • Known chromosomal abnormality (e.g. translocation)
  • Pre-implantation genetic diagnosis requiring blastocyst biopsy


  • University of California San Francisco
    San Francisco California 94115 United States
  • University of Oklahoma
    Oklahoma City Oklahoma 73104 United States

Lead Scientist

  • Marcelle I Cedars, MD
    Professor, Ob/Gyn, Reproductive Sciences. Authored (or co-authored) 215 research publications


in progress, not accepting new patients
Start Date
Completion Date
Yale University
Study Type
Last Updated