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Updated: Jun 24, 2026
Cryopreservation of Preimplantation Embryos of Cattle, Sheep, and Goats
Published on: August 5, 2011
Embryo cryopreservation rescues cycles with premature luteinization
Bruce S Shapiro1, Said T Daneshmand, Forest C Garner
1Fertility Center of Las Vegas, University of Nevada School of Medicine, 8851 West Sahara Avenue, Las Vegas, Nevada 89117, USA. bsshapiro@aol.com
Objective:
To determine whether embryo cryopreservation in cycles with elevated preovulatory P followed by thaw, extended culture, and transfer results in greater ongoing pregnancy rates than fresh blastocyst transfer.
Design:
Retrospective matched cohort study.
Setting:
Private fertility center.
Patient(S):
The study group consisted of 118 consecutive thaws of bipronucleate (2PN) oocytes derived from autologous cycles with elevated preovulatory P, resulting in 95 blastocyst transfers. The control group was selected by matching on the number of 2PN oocytes and patient age and consisted of 118 fresh cycles with elevated preovulatory P, including 108 fresh autologous blastocyst transfers. All patients were <41 years old at the time of stimulation.
Intervention(S):
None.
Main Outcome Measure(S):
Implantation and ongoing pregnancy rates.
Result(S):
The study group had significantly fewer blastocysts per 2PN oocyte than the control group (19.7% vs. 36.8%, respectively) and a significantly greater cancellation rate (19.5% vs. 8.5%, respectively). However, the ongoing pregnancy rate per cycle was significantly higher in the study group than in the control group (56.8% vs. 32.2%, respectively), resulting from greater rates of implantation (56.8% vs. 26.9%, respectively) and of ongoing pregnancy per transfer (70.5% vs. 35.2%, respectively).
Conclusion(S):
In cycles with elevated preovulatory P, the probabilities of implantation and ongoing pregnancy are increased if all 2PN oocytes are cryopreserved and subsequently thawed and cultured to the blastocyst stage before transfer.
