Cryopreservation of day 2-3 embryos by vitrification yields better outcome than slow freezing

Jacob Levron*, Oshrit Leibovitz, Masha Brengauz, Hila Gitman, Gil M. Yerushalmi, Eldad Katorza, Itai Gat, Shai E. Elizur

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Objective: To compare the outcome of vitrification versus slow freezing cryopreservation for cleavage stage day 2-3 embryos. Design: A retrospective observational study. Setting: All thawed embryos assisted reproduction cycles between January 2010 and December 2012 at a single IVF laboratory of a Tertiary Medical Center. Patients: Five hundred and thirty-nine cycles of day 2-3 thawed embryos. Interventions: In 327 of the thawed cycles, the embryos were vitrified and in 212 of the cycles the embryos were derived from slow freezing embryos. Main outcomes measure: Embryo survival rate, blastomere surviving rate and pregnancy rate. Results: Embryo survival rate was significantly higher after vitrification compared with slow freezing (81.6%, 647/793 versus 70.0%, 393/562 embryos, p<0.0001). The clinical pregnancy rate per ET was significantly higher following vitrification compared to slow freezing, 20.0%, 63/314 versus 11.9%, 23/193, respectively (p=0.02). Conclusions: Vitrification of day 2-3 cleavage stage embryos yields better cycle outcome in all the parameters compared to slow freezing.

Original languageEnglish
Pages (from-to)202-204
Number of pages3
JournalGynecological Endocrinology
Issue number3
StatePublished - Mar 2014
Externally publishedYes


  • Assisted reproductive technology
  • Infertility
  • Ovulation induction
  • Pregnancy


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