title: The factors affecting the outcome of frozen-thawed embryo transfer cycle.
abstract: OBJECTIVE
  To determine the impact of the clinical and embryological factors on the pregnancy outcome of frozen-thawed embryo transfer.
  
  
  METHODS
  The data of 247 frozen-thawed embryo transfer cycles were assessed at Royan Institute from March 2006 to March 2008. Appropriate statistical analysis was performed using Student t test and Chi-square or Fisher exact test. Forward logistic regression was done to predict the individual impact of factors on the success of frozen embryo transfer.
  
  
  RESULTS
  According to our results, 1,523 frozen embryos were thawed with a survival rate of 79.8%. The overall chemical and clinical pregnancy rates per embryo transfer cycle were 28.1% and 26.3%, respectively. A total of 71 gestational sacs were implanted (7.9%). The pregnancy outcome was higher in women who were stimulated with the gonadotrophin releasing hormone agonist long protocol, treated by a combination of follicle stimulating hormone and luteinizing hormone, who had endometrial thickness greater than or equal to 8mm on the embryo transfer day, and who had positive fresh-cycle pregnancy test.
  
  
  CONCLUSIONS
  Protocol type, gonadotrophin preparations, fresh-cycle outcome, endometrial thickness and the numbers of obtained oocytes, embryos, and high-quality thawed embryos transferred are the factors affecting pregnancy outcome of frozen-thawed embryo transfer.
authors.affiliation: Endocrinology and Female Infertility Department, Royan Institute for Reproductive Biomedicine, Culture and Research, Tehran, Iran. ashrafim@royaninstitute.org
authors.forename: Mahnaz
authors.initials: M
authors.lastname: Ashrafi
authors.forename: Nadia
authors.initials: N
authors.lastname: Jahangiri
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Hassani
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Akhoond
authors.forename: Tahereh
authors.initials: T
authors.lastname: Madani
mesh_terms: D000293:Adolescent; D000328:Adult; D015925:Cryopreservation; D010064:Embryo Implantation / Q000187:drug effects; D004624:Embryo Transfer / Q000379:methods*; D004717:Endometrium / Q000033:anatomy & histology; D005260:Female; D005640:Follicle Stimulating Hormone / Q000627:therapeutic use; D007987:Gonadotropin-Releasing Hormone / Q000819:agonists; D006801:Humans; D016015:Logistic Models; D007986:Luteinizing Hormone / Q000627:therapeutic use; D011247:Pregnancy; D018873:Pregnancy Rate; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone