Clinical outcomes following cryopreservation of blastocysts by vitrification or slow freezing: a population-based cohort study

Abstract

STUDY QUESTION: What are the clinical efficacy and perinatal outcomes following transfer of vitrified blastocysts compared with transfer of fresh or of slow frozen blastocysts? SUMMARY ANSWER: Compared with slow frozen blastocysts, vitrified blastocysts resulted in significantly higher clinical pregnancy and live delivery rates with similar perinatal outcomes at population level. WHAT IS KNOWN ALREADY: Although vitrification has been reported to be associated with significantly increased post-thaw survival rates compared with slow freezing, there has been a lack of general consensus over which method of cryopreservation (vitrification versus slow freezing) is most appropriate for blastocysts..