title: Clinical predictors of human blastocyst formation and pregnancy after extended embryo culture and transfer.
abstract: OBJECTIVE
  To determine the clinical factors associated with blastocyst development and pregnancy.
  
  
  METHODS
  Evaluation of a prospectively collected IVF database.
  
  
  METHODS
  An academic IVF practice.
  
  
  METHODS
  Couples (n = 529) undergoing their first IVF cycle who qualified for extended embryo culture (more than six zygotes) over the past 5 years.
  
  
  METHODS
  Seven or eight zygotes were cultured for 5 days, assessed for quality, and then transferred with excess zygotes cryopreserved at the pronuclear stage.
  
  
  METHODS
  Clinical predictors of blastocyst development and pregnancy.
  
  
  RESULTS
  The mean blastocyst development rate was 49.8%, with a median number of total and good-quality blastocysts of 4 and 2, respectively. Clinical factors that were significantly associated with good-quality blastocyst formation were younger female age, increased parity, standard insemination, and lower doses of gonadotropins. Clinical factors that were significantly associated with successful pregnancy were younger female age, higher antral follicle counts, greater numbers of total and good-/excellent-quality blastocysts, and absence of male factor infertility.
  
  
  CONCLUSIONS
  Several clinical factors are associated with the development of good-quality blastocysts after extended embryo culture and successful pregnancy outcome. These patient and cycle characteristics may be very useful in selecting the best candidates for extended embryo culture and single blastocyst transfers, thus optimizing outcomes while reducing the risks associated with multiple pregnancies.
authors.affiliation: Department of Obstetrics and Gynecology, Division of Reproductive Endocrinology, University of Iowa College of Medicine, Iowa City, Iowa, USA.
authors.forename: Mika R
authors.initials: MR
authors.lastname: Thomas
authors.forename: Amy E
authors.initials: AE
authors.lastname: Sparks
authors.forename: Ginny L
authors.initials: GL
authors.lastname: Ryan
authors.forename: Bradley J
authors.initials: BJ
authors.lastname: Van Voorhis
mesh_terms: D000328:Adult; D003376:Counseling; D015925:Cryopreservation; D016208:Databases, Factual; D046149:Embryo Culture Techniques / Q000379:methods* / Q000592:standards; D004624:Embryo Transfer / Q000379:methods* / Q000592:standards; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods* / Q000592:standards; D006801:Humans; D007247:Infertility, Female / Q000628:therapy*; D011237:Predictive Value of Tests; D011247:Pregnancy; D011256:Pregnancy Outcome; D055815:Young Adult; D015053:Zygote / Q000166:cytology