Related Experiment Videos
A comparison of day 5 and day 6 blastocyst transfers
B S Shapiro1, K S Richter, D C Harris
1Fertility Center of Las Vegas, Las Vegas, Nevada 89117, USA.
Objective:
To compare implantation and pregnancy rates according to the day of embryo transfer (day 5 or 6 after oocyte retrieval) when transfer was postponed until expanded blastocysts developed.
Design:
Retrospective clinical study.
Setting:
Private ART center.
Patient(S):
One-hundred and eighty-three women undergoing blastocyst-stage embryo transfer following in vitro fertilization.
Intervention(S):
Bipronucleate oocytes were grown for up to 144 hours and subsequently transferred only when at least one embryo attained the expanded blastocyst stage.
Main Outcome Measure(S):
Implantation and pregnancy rates.
Result(S):
Blastocysts transferred on day 5 implanted at nearly twice the rate of blastocysts transferred on day 6 (36.3% vs. 19.0%). Pregnancy rates were also almost twice as high among the day 5 transfer patients (59.3% vs. 32.3%). In addition, more blastocysts developed (3.6 vs. 2.4), and more were transferred (2.7 vs. 2.3) to the day 5 transfer patients, although the proportion of expanded blastocysts among the blastocysts that were transferred was the same for the two groups (91.7% vs. 93.6%).
Conclusion(S):
Embryos that develop to the expanded blastocyst stage and are transferred on day 5 after retrieval are approximately twice as likely to implant compared to those for which expansion and transfer are delayed until day 6.