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The number of eight-cell embryos is a key determinant for selecting day 3 or day 5 transfer
C Racowsky1, K V Jackson, N A Cekleniak
1Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA. cracowsky@bics.bwh.harvard.edu
Objective:
To select patients for day 3 vs. day 5 embryo transfer.
Design:
Retrospective analysis of assisted reproduction technology (ART) cycles comparing outcomes of day 3 and day 5 transfers.
Setting:
ART program of Brigham and Women's Hospital.
Patient(S):
Patients with day 3 or day 5 embryo transfers (n = 221 and 141, respectively).
Intervention(S):
Cycles with eight or more zygotes were stratified by the number of eight-cell embryos available on day 3 (none, one or two, or three or more).
Main Outcome Measure(S):
Number of blastocysts, implantation rates, ongoing pregnancy rates, and number of fetal heart beats.
Result(S):
With no eight-cell embryos on day 3, 0% and 33% pregnancies resulted from day 5 vs. day 3 transfers. With one or two eight-cell embryos on day 3, ongoing and high order multiple rates were not different between day 3 and day 5 transfers. With three or more eight-cell embryos, day 5 transfer resulted in a decrease in multiple gestations but no difference in ongoing pregnancy rates compared with day 3 transfer.
Conclusion(S):
With no eight-cell embryos on day 3, a day 3 transfer is warranted. With one or two eight-cell embryos, any benefit of day 5 transfer appears to be equivocal. With three or more eight-cell embryos, day 5 transfer is recommended.