Developmentally delayed cleavage-stage embryos maintain comparable implantation rates in frozen embryo transfers.
OBJECTIVE
In fresh IVF cycles, embryos reaching the eight-cell stage on day 3 of development are thought to have a higher chance of implantation than those reaching this stage on day 4. To determine whether this difference persists after cryopreservation, we compared pregnancy and implantation rates between frozen embryo transfer (FET) cycles using delayed cleavage-stage embryos (cryopreserved day 4) and normal cleavage-stage embryos (cryopreserved day 3).


METHODS
Participants underwent FET between 2008 and 2012 using embryos cryopreserved on either day 3 (n = 76) or day 4 (n = 48), depending on the length of time needed to achieve the eight-cell stage. All embryos, regardless of day of cryopreservation, were thawed and transferred on the 4th day of vaginal progesterone following endometrial preparation with oral estradiol. Chi-square and Mann-Whitney U tests were used to compare patient demographics and cycle outcomes.


RESULTS
More women in the day 4 group had diminished ovarian reserve (44 vs 16 %, p = 0.003). Pregnancy outcomes in preceding fresh cycles were not different between the two groups. Pregnancy, implantation, and live birth rates following FET did not differ between the day 3 and day 4 groups.


CONCLUSIONS
This is the first study to address outcomes using day 3 versus day 4 cryopreserved embryos. Despite a higher prevalence of diminished ovarian reserve (DOR) in the day 4 group, delayed cleavage-stage embryos utilized in FET cycles performed as well as embryos growing at the normal rate, suggesting delayed embryo development does not affect embryo implantation as long as endometrial synchrony is maintained.
Department of Obstetrics and Gynecology, Division of Reproductive Endocrinology and Infertility, Keck School of Medicine, University of Southern California, 2020 Zonal Avenue, Room 534, Los Angeles, CA, 90033, USA. hburks@med.usc.edu.
Heather
H
Burks
Department of Obstetrics and Gynecology, Division of Reproductive Endocrinology and Infertility, Keck School of Medicine, University of Southern California, 2020 Zonal Avenue, Room 534, Los Angeles, CA, 90033, USA. Jennifer.Buckbinder@med.usc.edu.
Jennifer
J
Buckbinder
Department of Obstetrics and Gynecology, Division of Reproductive Endocrinology and Infertility, Keck School of Medicine, University of Southern California, 2020 Zonal Avenue, Room 534, Los Angeles, CA, 90033, USA. Mary.Francis-Hernandez@med.usc.edu.
Mary
M
Francis-Hernandez
Department of Obstetrics and Gynecology, Division of Reproductive Endocrinology and Infertility, Keck School of Medicine, University of Southern California, 2020 Zonal Avenue, Room 534, Los Angeles, CA, 90033, USA. Karine.Chung@med.usc.edu.
Karine
K
Chung
Department of Obstetrics and Gynecology, Division of Reproductive Endocrinology and Infertility, Kaiser Permanente, 4900 W. Sunset Boulevard, Los Angeles, CA, 90027, USA. Sami.Jabara@med.usc.edu.
Sami
S
Jabara
Department of Obstetrics and Gynecology, Division of Reproductive Endocrinology and Infertility, Keck School of Medicine, University of Southern California, 2020 Zonal Avenue, Room 534, Los Angeles, CA, 90033, USA. Kristin.Bendikson@med.usc.edu.
Kristin
K
Bendikson
Department of Obstetrics and Gynecology, Division of Reproductive Endocrinology and Infertility, Keck School of Medicine, University of Southern California, 2020 Zonal Avenue, Room 534, Los Angeles, CA, 90033, USA. rpaulson@med.usc.edu.
Richard
R
Paulson
D000282:Administration, Intravaginal; D000328:Adult; D001755:Blastocyst / Q000502:physiology*; D002970:Cleavage Stage, Ovum / Q000502:physiology; D015331:Cohort Studies; D015925:Cryopreservation / Q000379:methods*; D010064:Embryo Implantation / Q000502:physiology*; D004624:Embryo Transfer / Q000379:methods*; D005260:Female; D006801:Humans; D050498:Live Birth; D008875:Middle Aged; D011247:Pregnancy; D018873:Pregnancy Rate; D011374:Progesterone / Q000008:administration & dosage; D012189:Retrospective Studies; D016896:Treatment Outcome
D011374:Progesterone
Cleavage-stage embryo; Delayed embryo development; Embryo cryopreservation; Frozen embryo transfer