title: Frozen-Thawed Embryo Transfer Success Rate is Affected by Age and Ovarian Response at Oocyte Aspiration Regardless of Blastomere Survival Rate.
abstract: OBJECTIVE
  To identify the factors influencing the success of frozen-thawed embryo transfers, whether originating directly from current cycles or from their matching fresh cycles.
  
  
  METHODS
  Analysis of 273 frozen-thawed embryo transfer cycles and their matching fresh embryo transfer cycles, with respect to maternal, embryological and clinical factors, comparing successful to unsuccessful cycles.
  
  
  RESULTS
  The cumulative clinical pregnancy and live birth rates following fresh ET and corresponding FETs were 50.5% and 38.8%, respectively. No outcome measure differed between fresh and frozen ET's. Only maternal age, number of oocytes retrieved and fertilized, and number of cleaved embryos in the fresh cycle were correlated with a higher pregnancy or live birth rate in the FET cycle. None of the other parameters had any effect on the outcome. Pre-freezing embryo quality and blastomere survival rate had no effect on pregnancy/live birth rates.
  
  
  CONCLUSIONS
  Clinical pregnancy and live birth rates of fresh and frozen ETs were not significantly different. The only parameters that affected FET success were those resulting from the patient's age and ovarian reserve at the time of oocyte aspiration. Post-thawing blastomere survival rate and type of endometrial preparation for FET did not affect the success rate.
authors.affiliation: Reproductive Endocrinology Divisions and IVF Units, Department of Obstetrics & Gynecology, Hadassah-Hebrew University Medical Center, Mount Scopus and Ein Kerem, Jerusalem, Israel.
authors.forename: Yuval
authors.initials: Y
authors.lastname: Bdolah
authors.affiliation: Department of Obstetrics & Gynecology, Chaim Sheba Medical Center, Tel Hashomer, Israel.
authors.forename: Roni
authors.initials: R
authors.lastname: Zemet
authors.affiliation: Reproductive Endocrinology Divisions and IVF Units, Department of Obstetrics & Gynecology, Hadassah-Hebrew University Medical Center, Mount Scopus and Ein Kerem, Jerusalem, Israel.
authors.forename: Einat
authors.initials: E
authors.lastname: Aizenman
authors.affiliation: Reproductive Endocrinology Divisions and IVF Units, Department of Obstetrics & Gynecology, Hadassah-Hebrew University Medical Center, Mount Scopus and Ein Kerem, Jerusalem, Israel.
authors.forename: Francine
authors.initials: F
authors.lastname: Lossos
authors.affiliation: The Hebrew University Medical School, Jerusalem, Israel.
authors.forename: Tali Bdolah
authors.initials: TB
authors.lastname: Abram
authors.affiliation: Infertility and IVF Unit, Beilinson's Hospital for Women, Rabin Medical Center, Petach Tikva 49100, Israel and the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Yoel
authors.initials: Y
authors.lastname: Shufaro
keywords: Frozen thawed embryo transfer; Reproductive outcomes