title: Blastocoele re-expansion time in vitrified-warmed cycles is a strong predictor of clinical pregnancy outcome.
abstract: OBJECTIVE
  To assess the predictive value of blastocoele re-expansion time in clinical pregnancy outcome in vitrified-warmed cycles.
  
  
  METHODS
  Data on 468 single vitrified-thawed blastocyst transfer cycles (in patients aged <38 years) carried out from January 2012 through December 2012, at the Reproductive Medicine Center, Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region, were analyzed. Vitrified-warmed blastocysts were divided into three groups according to blastocoele re-expansion time: group A, <1 h; group B, 1-2 h; and group C, >2 h, and the clinical pregnancy outcomes (i.e. live birth rate, miscarriage rate and occurrence of singleton pregnancies) compared between the groups.
  
  
  RESULTS
  Significant differences were observed in the implantation/clinical pregnancy rate between groups A, B and C (70.10%, 51.76% and 28.74%, respectively, P < 0.01). There was a significant linear decline in this rate with increasing blastocyst re-expansion time. The rate of miscarriage also tended to increase with increasing blastocyst re-expansion time, but the difference was not statistically significant (P > 0.05). Of the pregnant patients, no significant difference was observed in the rates of monozygotic twins and ectopic pregnancy between the three groups. For the newborns, similar live birth, low-birthweight and premature delivery rates were observed between the groups.
  
  
  CONCLUSIONS
  Timing of blastocoele re-expansion in vitrified-warmed cycles is a strong predictor of clinical pregnancy outcome. The faster the re-expansion of the blastocoele, the higher the developmental potential of the blastocysts.
authors.affiliation: Reproductive Medicine center, Maternal and Child Health Hospital, Obstetrics and Gynecology Hospital of Guangxi Zhuang Autonomous Region, Nanning, China.
authors.forename: Ruoyun
authors.initials: R
authors.lastname: Lin
authors.affiliation: Reproductive Medicine center, Maternal and Child Health Hospital, Obstetrics and Gynecology Hospital of Guangxi Zhuang Autonomous Region, Nanning, China.
authors.forename: Guixue
authors.initials: G
authors.lastname: Feng
authors.affiliation: Reproductive Medicine center, Maternal and Child Health Hospital, Obstetrics and Gynecology Hospital of Guangxi Zhuang Autonomous Region, Nanning, China.
authors.forename: Jinhui
authors.initials: J
authors.lastname: Shu
authors.affiliation: Reproductive Medicine center, Maternal and Child Health Hospital, Obstetrics and Gynecology Hospital of Guangxi Zhuang Autonomous Region, Nanning, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Zhang
authors.affiliation: Reproductive Medicine center, Maternal and Child Health Hospital, Obstetrics and Gynecology Hospital of Guangxi Zhuang Autonomous Region, Nanning, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Zhou
authors.affiliation: Reproductive Medicine center, Maternal and Child Health Hospital, Obstetrics and Gynecology Hospital of Guangxi Zhuang Autonomous Region, Nanning, China.
authors.forename: Xianyou
authors.initials: X
authors.lastname: Gan
authors.affiliation: Reproductive Medicine center, Maternal and Child Health Hospital, Obstetrics and Gynecology Hospital of Guangxi Zhuang Autonomous Region, Nanning, China.
authors.forename: Caizhu
authors.initials: C
authors.lastname: Wang
authors.affiliation: Reproductive Medicine center, Maternal and Child Health Hospital, Obstetrics and Gynecology Hospital of Guangxi Zhuang Autonomous Region, Nanning, China.
authors.forename: Huanhua
authors.initials: H
authors.lastname: Chen
mesh_terms: D000328:Adult; D001755:Blastocyst / Q000502:physiology*; D004624:Embryo Transfer / Q000379:methods*; D005260:Female; D006801:Humans; D011247:Pregnancy; D011256:Pregnancy Outcome; D011379:Prognosis; D013997:Time Factors; D058989:Vitrification
keywords: blastocoele re-expansion time; blastocyst; vitrification; vitrified-warmed cycle