title: Multiple pregnancy after single or multiple embryo transfer performed according to Korean guidelines.
abstract: OBJECTIVE
  To assess compliance with Korean guidelines for embryo transfer, the possible reasons for non-compliance, and multiple pregnancies according to each specific condition in compliant cycles.
  
  
  METHODS
  A single-institution, retrospective study was conducted of 256 fresh in vitro fertilization cycles during 2012-2014. To assess compliance with Korean guidelines, the maximum recommended number of embryos transferred (according to criteria of age, transfer day, and presence of favorable conditions) was compared with the actual number of embryos transferred. Clinical pregnancy rate (PR) was assessed as the percentage of pregnant women resulting from each set of transfer conditions, including the number of embryos transferred. The multiple pregnancy rate (MPR) was calculated as the percentage of pregnant women with a multifetal pregnancy.
  
  
  RESULTS
  The compliance rate with the Korean guidelines was 96.5% (247/256). Non-compliance occurred in nine cycles owing to poor embryo quality, repeated implantation failure, or hostile endometrium. In compliant cycles, the PR was 31.2% (77/247), and the MPR was 27.3% (21/77; 20 twins and one triplet). Higher MPR was noted in two types of transfer conditions: transfer of three cleavage embryos in women aged 35-39 years with favorable conditions (66.7%; primarily from those aged 35-37 years) and transfer of two blastocysts in women aged ≥40 years with favorable conditions (50%).
  
  
  CONCLUSIONS
  Under the Korean guidelines, compliance rate was high in our center. Multiple pregnancies occurred primarily in group with favorable conditions. In high-risk groups for multiple pregnancies, reducing number of embryos transferred should be considered than suggested in the guideline.
authors.affiliation: Department of Obstetrics and Gynecology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea.
authors.forename: E Jung
authors.initials: EJ
authors.lastname: Han
authors.affiliation: Department of Obstetrics and Gynecology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea.
authors.forename: Seul Ki
authors.initials: SK
authors.lastname: Kim
authors.affiliation: Department of Obstetrics and Gynecology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea.; Department of Obstetrics and Gynecology, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Jung Ryeol
authors.initials: JR
authors.lastname: Lee
authors.affiliation: Department of Obstetrics and Gynecology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea.; Department of Obstetrics and Gynecology, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Byung Chul
authors.initials: BC
authors.lastname: Jee
authors.affiliation: Department of Obstetrics and Gynecology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea.; Department of Obstetrics and Gynecology, Seoul National University College of Medicine, Seoul, Korea.; Department of Obstetrics and Gynecology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Chang Suk
authors.initials: CS
authors.lastname: Suh
authors.affiliation: Department of Obstetrics and Gynecology, Seoul National University College of Medicine, Seoul, Korea.; Department of Obstetrics and Gynecology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Seok Hyun
authors.initials: SH
authors.lastname: Kim
keywords: Embryo transfer; Guidelines; Multiple pregnancy
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