title: Transfer of cryopreserved-thawed pre-embryos in a natural cycle or a programmed cycle with exogenous hormonal replacement yields similar pregnancy results.
abstract: OBJECTIVE
  To examine the results of 7 years of thawed ET during natural or controlled cycles using exogenous steroids.
  
  
  METHODS
  Retrospective evaluation to compare implantation and pregnancy rates with two protocols for transfer of cryopreserved-thawed pre-embryos.
  
  
  METHODS
  Tertiary care academic center.
  
  
  METHODS
  From January 1987 to December 1993, 521 patients who were < 40 years of age underwent 628 thawed embryo transfers.
  
  
  METHODS
  Pregnancy and implantation rates per thawed embryo transfer cycle.
  
  
  RESULTS
  A total 1,987 pre-embryos survived the thawing process and were used in 628 thaw-transfer cycles. Transfer was performed in a natural cycle 2 days after the LH peak or on day 17 of a programmed cycle using a GnRH-agonist and hormone replacement therapy protocol; 182 pregnancies were established (182/628; 29%). Similar pregnancy rates were seen in the natural cycle (112/398; 28%) and the programmed cycle (70/230; 30%). The implantation rates were similar in the two methods of transfer cycles (11.9% versus 10.3%, natural versus programmed cycle). There were no significant differences in clinical or ongoing pregnancy rates in a natural or programmed cycle, correcting for the number of cryopreserved-thawed pre-embryos transferred. Patient's age at the time of freezing and the number of cryopreserved-thawed pre-embryos transferred are more important determinants of pregnancy than the type of cycle in which transfer occurs.
  
  
  CONCLUSIONS
  Transferring cryopreserved-thawed pre-embryos in a natural or programmed cycle yields similar pregnancy results.
authors.affiliation: Jones Institute for Reproductive Medicine, Department of Obstetrics and Gynecology, Eastern Virginia Medical School, Norfolk.
authors.forename: J T
authors.initials: JT
authors.lastname: Queenan
authors.forename: L L
authors.initials: LL
authors.lastname: Veeck
authors.forename: H J
authors.initials: HJ
authors.lastname: Seltman
authors.forename: S J
authors.initials: SJ
authors.lastname: Muasher
mesh_terms: D000328:Adult; D000375:Aging / Q000502:physiology; D015925:Cryopreservation; D010064:Embryo Implantation; D004624:Embryo Transfer; D005260:Female; D006728:Hormones / Q000627:therapeutic use*; D006801:Humans; D008597:Menstrual Cycle; D011247:Pregnancy; D012044:Regression Analysis; D012189:Retrospective Studies
chemical_list: D006728:Hormones