Blastocyst score affects implantation and pregnancy outcome: towards a single blastocyst transfer

Fertil Steril. 2000 Jun;73(6):1155-8. doi: 10.1016/s0015-0282(00)00518-5.


Objective: To determine the relationship between blastocyst score and pregnancy outcome.

Design: Retrospective review of blastocyst transfer in an IVF clinic.

Setting: Private assisted reproductive technology unit.

Patient(s): 107 patients undergoing blastocyst culture and transfer of two embryos.

Intervention(s): Culture of all pronucleate embryos in sequential media to the blastocyst stage (day 5), followed by transfer of two blastocysts.

Main outcome measure(s): Implantation rates, pregnancy rates, and twinning were analyzed.

Result(s): When a patient received two top-scoring blastocysts (64% of patients), implantation and pregnancy rates were 70% and 87%, respectively. The twinning rate in this group was 61%. When only one top-quality blastocyst was available for transfer (21% of patients), the implantation and pregnancy rates were 50% and 70%. The twinning rate for this group was 50%. In contrast, when only low-scoring blastocysts were available for transfer (15% of patients), implantation and pregnancy rates were 28% and 44%, and the twinning rate was 29%. No monozygotic twins were observed in this group of patients.

Conclusion(s): The ability to transfer one high-scoring blastocyst should lead to pregnancy rates greater than 60%, without the complication of twins.

MeSH terms

  • Adult
  • Blastocyst / physiology*
  • Embryo Implantation / physiology*
  • Embryo Transfer*
  • Female
  • Fertilization in Vitro
  • Humans
  • Pregnancy
  • Pregnancy Outcome*
  • Pregnancy Rate
  • Pregnancy, Multiple
  • Retrospective Studies
  • Twins