title: Selection of embryos for day-3 transfer at the pronuclear-stage and pronuclear-stage cryopreservation results in high delivery rates in fresh and frozen cycles.
abstract: OBJECTIVE
  Evaluate IVF-ET outcome data for a unique culture and cryopreservation strategy.
  
  
  METHODS
  Retrospective study of 92 patients. Embryos for day-3 transfer were selected at pronuclear-stage; all extra zygotes were cryopreserved at pronuclear-stage.
  
  
  RESULTS
  Delivery rates for Anonymous Oocyte Donation (Group I), patients <35 years (Group II), and 35-38 years (Group III) were 52.9%, 61.5%, and 51.7% for fresh and 38.5%, 33.3%, and 40.0% for frozen transfer. Deliveries per retrieval were 82.3%, 71.8%, and 58.6%. Only 0.88, 0.80, and 0.61 more zygotes were cultured than what were used for fresh transfer. Singleton, twin, and triplet rates were 64.6%, 31.2%, and 4.2% for fresh and 69.2%, 30.8%, and 0% for frozen.
  
  
  CONCLUSIONS
  Selection of day-3 transfer embryos at the pronuclear-stage and cryopreservation of extra zygotes results in high delivery rates in fresh and frozen cycles. This approach optimizes deliveries per retrieval and provides many patients with more than one pregnancy per retrieval.
authors.affiliation: Center for Reproductive Medicine, Mayo Clinic Scottsdale, Thunderbird Women's Health Center, 13737 North 92nd Street, Scottsdale, Arizona 85260, USA. dhammitt@mayo.edu
authors.forename: Diane G
authors.initials: DG
authors.lastname: Hammitt
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Sattler
authors.forename: Misty L
authors.initials: ML
authors.lastname: Manes
authors.forename: Anita P
authors.initials: AP
authors.lastname: Singh
mesh_terms: D001755:Blastocyst / Q000166:cytology / Q000502:physiology*; D015925:Cryopreservation; D004624:Embryo Transfer; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods*; D005831:Genital Diseases, Female / Q000145:classification; D006801:Humans; D007248:Infertility, Male / Q000145:classification; D008297:Male; D018587:Oocyte Donation; D011247:Pregnancy; D011256:Pregnancy Outcome; D012189:Retrospective Studies; D015053:Zygote / Q000166:cytology / Q000502:physiology