title: Single-embryo transfer of vitrified-warmed blastocysts yields equivalent live-birth rates and improved neonatal outcomes compared with fresh transfers.
abstract: OBJECTIVE
  To compare pregnancy and neonatal outcomes after fresh and vitrified-warmed single-blastocyst transfers.
  
  
  METHODS
  Retrospective study.
  
  
  METHODS
  Private in vitro fertilization (IVF) clinic.
  
  
  METHODS
  1,209 infertile patients who underwent a total of 1,157 fresh and 645 vitrified-warmed embryo transfers.
  
  
  METHODS
  Day-5 single-blastocyst transfers using fresh or vitrified-warmed (Cryotop method) grade I and grade II embryos.
  
  
  METHODS
  Fetal heart pregnancy rate, live-birth rate, gestational age, and live-birth weight.
  
  
  RESULTS
  The overall blastocyst thaw survival rate was 94.4% and was not significantly different between blastocyst grades or developmental stages. Similar clinical outcomes were achieved for fresh and vitrified-warmed blastocyst transfers; for example, grade I blastocysts had a live-birth rate of 52.8% versus 55.3%, respectively, and grade II blastocysts had a rate of 34.9% versus 30.4%, respectively. Significantly improved neonatal outcomes were evident for vitrified-warmed blastocyst transfers for gestational age, being on average 0.3 weeks longer, and for live-birth weight with babies born on average 145 g heavier (3,296 g versus 3,441 g for fresh and vitrified-warmed groups, respectively), as compared with fresh transfers.
  
  
  CONCLUSIONS
  Embryo transfer of vitrified-warmed blastocysts yields equivalent live-birth rates and improved neonatal outcomes compared with fresh transfers.
authors.affiliation: Genea, Sydney, New South Wales, Australia. Electronic address: tammie.roy@genea.com.au.
authors.forename: Tammie K
authors.initials: TK
authors.lastname: Roy
authors.affiliation: Genea, Sydney, New South Wales, Australia.
authors.forename: Cara K
authors.initials: CK
authors.lastname: Bradley
authors.affiliation: Genea, Sydney, New South Wales, Australia.
authors.forename: Mark C
authors.initials: MC
authors.lastname: Bowman
authors.affiliation: Genea, Sydney, New South Wales, Australia.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: McArthur
mesh_terms: D000328:Adult; D001755:Blastocyst; D004624:Embryo Transfer / Q000379:methods / Q000639:trends*; D005260:Female; D006358:Hot Temperature / Q000627:therapeutic use*; D006801:Humans; D007231:Infant, Newborn; D011247:Pregnancy; D018873:Pregnancy Rate / Q000639:trends*; D012189:Retrospective Studies; D056826:Single Embryo Transfer / Q000379:methods / Q000639:trends*; D058989:Vitrification
keywords: Assisted reproduction; blastocyst; human; single-embryo transfer; vitrification