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Clin Exp Reprod Med. 2012 Sep;39(3):114-117. English. Original Article.
Han AR , Park CW , Lee HS , Yang KM , Song IO , Koong MK .
Department of Obstetrics and Gynecology, Kyungpook National University Hospital, Daegu, Korea.
Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, Cheil General Hospital and Women's Healthcare Center, Kwandong University College of Medicine, Seoul, Korea. novak21c@yahoo.co.kr
Laboratory of Reproductive Biology and Infertility, Cheil General Hospital and Women's Healthcare Center, Kwandong University College of Medicine, Seoul, Korea.
Abstract

OBJECTIVE: It is well known that fresh blastocyst transfer results in better pregnancy outcomes with a smaller number of transferred embryos compared with cleavage stage embryo transfer. However, in terms of frozen-thawed blastocyst transfer, only a few studies are available. We aimed to evaluate clinical outcomes of frozen-thawed embryo transfer (FET) with blastocysts. METHODS: Retrospective analysis of FET cycles with blastocysts (B-FET) between Jan 2007 and June 2009 was performed. Age-matched FET cycles with cleavage stage embryos (C-FET) during the same period were collected as controls. A total of 58 B-FET cycles were compared with 172 C-FET cycles and also compared with those of post-thaw extended culture blastocysts from frozen pronuclear stage embryos (22 cycles). RESULTS: There was no difference in the patient characteristics of each group. The embryos' survival rates after thawing were comparable (>90%) and there was no difference in the implantation rate or clinical and ongoing pregnancy rate among the three groups. CONCLUSION: In FET, blastocyst transfers may not present better pregnancy outcomes than cleavage stage embryo transfers. A further large-scale prospective study is needed.

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