title: Oocyte efficiency: does live birth rate differ when analyzing cryopreserved and fresh oocytes on a per-oocyte basis?
abstract: OBJECTIVE
  To compare the efficiency of oocyte cryopreservation (OC) and IVF using the metric "live births per mature oocyte retrieved."
  
  
  METHODS
  Retrospective analysis.
  
  
  METHODS
  University-based fertility center.
  
  
  METHODS
  Forty women who underwent OC with thaw attempt between 2004 and 2010; 25 autologous and 15 donor-oocyte treatments were included. One thousand nine hundred eight women underwent their first, fresh conventional IVF treatment between 2004 and 2010; 1,392 used autologous oocytes, and 516 used donor oocytes. Autologous and donor-oocyte cycles were analyzed separately. All oocytes were obtained from women <age 40 years old.
  
  
  METHODS
  None.
  
  
  METHODS
  Live-birth rate per mature oocyte retrieved (primary outcome), live-birth rate per ET, and blastocyst formation rate.
  
  
  RESULTS
  When OC/thaw cycles were compared with fresh IVF attempts, there was no significant difference in live-birth rate per mature oocyte retrieved (2.7% vs. 4.2%, respectively) or live-birth rate per ET (45.8% vs. 51.9%). Significantly more oocytes were harvested in the OC versus fresh IVF cycles (21 vs. 16); however, fewer blastocysts developed (3.9 vs. 6.3). Thus, we noted an age-independent approximate twofold decrease in blastocyst formation in the OC group.
  
  
  CONCLUSIONS
  Our data suggest that while assisted reproductive technology remains an inefficient process, OC may be approaching fresh IVF when live birth is the primary consideration. However, OC may negatively impact the potential for blastocyst formation.
authors.affiliation: New York University Fertility Center, New York University School of Medicine, New York, New York 10016, USA. Kara.Goldman@med.nyu.edu
authors.forename: Kara N
authors.initials: KN
authors.lastname: Goldman
authors.forename: Nicole L
authors.initials: NL
authors.lastname: Noyes
authors.forename: Jaime M
authors.initials: JM
authors.lastname: Knopman
authors.forename: Caroline
authors.initials: C
authors.lastname: McCaffrey
authors.forename: James A
authors.initials: JA
authors.lastname: Grifo
mesh_terms: D000328:Adult; D001723:Birth Rate; D015925:Cryopreservation / Q000379:methods / Q000592:standards / Q000706:statistics & numerical data; D004624:Embryo Transfer / Q000379:methods* / Q000592:standards / Q000706:statistics & numerical data*; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods; D006801:Humans; D007231:Infant, Newborn; D009865:Oocytes; D011247:Pregnancy; D018873:Pregnancy Rate; D012189:Retrospective Studies; D016896:Treatment Outcome
keywords: Oocyte cryopreservation; clinical efficiency; fertility preservation