title: Length of time of embryo storage does not negatively influence pregnancy rates after thawing and transfer.
abstract: OBJECTIVE
  To determine if longer storage of embryos in a cryopreserved state negatively affects the chance of successful implantation following thawing and transfer.
  
  
  METHODS
  A retrospective cohort analysis of frozen-thawed embryos that had been donated to recipients. Four time periods were evaluated.
  
  
  RESULTS
  No significant decrease in pregnancy or implantation rates was found in the longest freezing group (> or =6 years). In fact, if there was a trend, it was for improved pregnancy rates with longer storage. One of the successes was from embryos stored about 12 years.
  
  
  CONCLUSIONS
  Hopefully these data and results from other IVF centers will influence those countries having a mandatory discarding policy to reconsider and lift these restrictions, especially to increase the pool of embryos available for donation.
authors.affiliation: The University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School at Camden, Cooper Hospital/University Medical Center, Department of Obstetrics and Gynecology, Division of Reproductive Endocrinology & Infertility, Camden, NJ, USA. laurie@ccivf.com
authors.forename: J H
authors.initials: JH
authors.lastname: Check
authors.forename: D
authors.initials: D
authors.lastname: Summers-Chase
authors.forename: W
authors.initials: W
authors.lastname: Yuan
authors.forename: K
authors.initials: K
authors.lastname: Swenson
authors.forename: D
authors.initials: D
authors.lastname: Horwath
mesh_terms: D015331:Cohort Studies; D015925:Cryopreservation; D010064:Embryo Implantation; D004624:Embryo Transfer; D005260:Female; D006801:Humans; D018587:Oocyte Donation; D011247:Pregnancy; D018873:Pregnancy Rate; D012189:Retrospective Studies; D013997:Time Factors