title: Value of transferring embryos that show no evidence of fertilization at the time of fertilization assessment.
abstract: OBJECTIVE
  To determine the value of transferring embryos formed from nonpronuclear (0PN) zygotes.
  
  
  METHODS
  A case-control study.
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  The current study was a retrospective analysis of embryo transfers of just 0PN embryos using fresh cleavage-stage embryos (0PN cleavage fresh), frozen-thawed cleavage-stage 0PN embryos (0PN cleavage frozen), and frozen 0PN blastocyst-stage embryos (0PN blast frozen).
  
  
  METHODS
  To study the effect of 0PN transfer, comparison groups were used: fresh cycles of 2PN (2PN cleavage fresh-C) and frozen-thawed cycles cleavage-stage (2PN cleavage frozen-C) and blastocyst-stage (2PN blast frozen-C). Comparison groups were matched for cycle and patient characteristics to the 0PN group.
  
  
  METHODS
  Implantation rate (IR), pregnancy rate, and transferable embryo rate.
  
  
  RESULTS
  For fresh cycles, the IR in the 0PN cleavage fresh was lower than that in the 2PN cleavage fresh-C (8.04% vs. 19.50%, respectively). For frozen-thawed cycles, the IR in the 0PN cleavage frozen was lower than that in the 2PN cleavage frozen-C (15.38% vs. 28.24%, respectively), but the IR in 0PN blast frozen was comparable to that of 2PN blast frozen-C (39.56% vs. 48.18%, respectively).
  
  
  CONCLUSIONS
  Transfer of 0PN embryos from fresh or frozen-thawed cycles results in pregnancies and live births. Nonpronuclear embryos have a lower IR than 2PN embryos, but if the embryos are cultured to the blastocyst stage and then are frozen, their IRs approach that of 2PN embryos in subsequent frozen-thawed cycles. The culture of 0PN embryos to the blastocyst stage may select for embryos with a near-normal IR.
authors.affiliation: Reproductive Medical Center, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, People's Republic of China; Key Laboratory of Assisted Reproduction, Ministry of Education, Beijing, People's Republic of China; Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproduction, Beijing, People's Republic of China.
authors.forename: Ming
authors.initials: M
authors.lastname: Li
authors.affiliation: Reproductive Medical Center, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, People's Republic of China; Key Laboratory of Assisted Reproduction, Ministry of Education, Beijing, People's Republic of China; Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproduction, Beijing, People's Republic of China.
authors.forename: Shengli
authors.initials: S
authors.lastname: Lin
authors.affiliation: Reproductive Medical Center, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, People's Republic of China; Key Laboratory of Assisted Reproduction, Ministry of Education, Beijing, People's Republic of China; Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproduction, Beijing, People's Republic of China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Reproductive Medical Center, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, People's Republic of China; Key Laboratory of Assisted Reproduction, Ministry of Education, Beijing, People's Republic of China; Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproduction, Beijing, People's Republic of China.
authors.forename: Jinliang
authors.initials: J
authors.lastname: Zhu
authors.affiliation: Reproductive Medical Center, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, People's Republic of China; Key Laboratory of Assisted Reproduction, Ministry of Education, Beijing, People's Republic of China; Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproduction, Beijing, People's Republic of China. Electronic address: bysylp@sina.com.
authors.forename: Ping
authors.initials: P
authors.lastname: Liu
authors.affiliation: Reproductive Medical Center, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, People's Republic of China; Key Laboratory of Assisted Reproduction, Ministry of Education, Beijing, People's Republic of China; Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproduction, Beijing, People's Republic of China.
authors.forename: Jie
authors.initials: J
authors.lastname: Qiao
mesh_terms: D001755:Blastocyst / Q000502:physiology*; D002681:China; D002970:Cleavage Stage, Ovum / Q000502:physiology*; D015925:Cryopreservation; D046149:Embryo Culture Techniques; D010064:Embryo Implantation; D004624:Embryo Transfer; D005260:Female; D005298:Fertility; D005307:Fertilization in Vitro; D006801:Humans; D007246:Infertility / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D011247:Pregnancy; D018873:Pregnancy Rate; D012189:Retrospective Studies; D016896:Treatment Outcome
keywords: 0PN; blastocyst culture; embryo transfer; implantation rate