The number of eight-cell embryos is a key determinant for selecting day 3 or day 5 transfer.
OBJECTIVE
To select patients for day 3 vs. day 5 embryo transfer.


METHODS
Retrospective analysis of assisted reproduction technology (ART) cycles comparing outcomes of day 3 and day 5 transfers.


METHODS
ART program of Brigham and Women's Hospital.


METHODS
Patients with day 3 or day 5 embryo transfers (n = 221 and 141, respectively).


METHODS
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).


METHODS
Number of blastocysts, implantation rates, ongoing pregnancy rates, and number of fetal heart beats.


RESULTS
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.


CONCLUSIONS
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.
Racowsky
C
C
Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA. cracowsky@bics.bwh.harvard.edu
Jackson
K V
KV
Cekleniak
N A
NA
Fox
J H
JH
Hornstein
M D
MD
Ginsburg
E S
ES
D000328:Adult; D001755:Blastocyst / Q000166:cytology; D010064:Embryo Implantation; D004624:Embryo Transfer / Q000379:methods*; D004622:Embryo, Mammalian / Q000166:cytology*; D005260:Female; D006801:Humans; D008423:Maternal Age; D011247:Pregnancy; D018873:Pregnancy Rate; D011272:Pregnancy, Multiple; D012189:Retrospective Studies; D013997:Time Factors