title: Supernumerary blastocyst cryopreservation: a key prognostic indicator for patients opting for an elective single blastocyst transfer (eSBT).
abstract: OBJECTIVE
  To determine if patients, less than 40 years of age with or without day 5 cryopreservation (d5 cryo), compromise their pregnancy rate (PR) by choosing an eSBT.
  
  
  METHODS
  Retrospective analysis
  
  
  METHODS
  University IVF center
  
  
  METHODS
  2,203 non-donor fresh IVF cycles in women <40 years of age from January 2004 to January 2010.
  
  
  METHODS
  None
  
  
  METHODS
  Eggs retrieved, Embryos cryopreserved, Implantation Rates, Clinical Pregnancy Rates, Live Birth Rates, Spontaneous Abortion Rates
  
  
  RESULTS
  Pregnancy outcomes in women <40 years with or without d5 cryo were compared according to whether patients underwent an eSBT versus a 2BT in non-donor fresh IVF cycles. Overall, eSBT was associated with elimination of twinning while maintaining a high clinical pregnancy rate in both groups with d5 cryo (75 % eSBT versus 72 % 2BT) and groups without d5 cryo (48 % eSBT versus 56 % 2BT).
  
  
  CONCLUSIONS
  In this study, patients <40 years of age have eliminated twinning by electively choosing to transfer a single blastocyst without compromising their PR if embryos are available for d5 cryo, and suffer only a non-statistically significant drop in their PR if there are no embryos available for d5 cryo in exchange for the benefit of eliminating the obstetrical risk of twinning.
authors.affiliation: NYU Fertility Center, New York University, Langone Medical Center, New York, NY 10016, USA. christine.mullin@gmail.com
authors.forename: Christine
authors.initials: C
authors.lastname: Mullin
authors.forename: Alan S
authors.initials: AS
authors.lastname: Berkeley
authors.forename: Jamie A
authors.initials: JA
authors.lastname: Grifo
mesh_terms: D000028:Abortion, Induced; D000328:Adult; D001755:Blastocyst / Q000166:cytology* / Q000502:physiology; D015925:Cryopreservation / Q000379:methods*; D010064:Embryo Implantation; D004624:Embryo Transfer / Q000379:methods*; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D050498:Live Birth; D054315:Oocyte Retrieval / Q000379:methods; D011247:Pregnancy; D011256:Pregnancy Outcome; D018873:Pregnancy Rate; D011379:Prognosis; D012189:Retrospective Studies; D038522:Twinning, Monozygotic