Selection of Embryos for Day-3 Transfer at the Pronuclear-Stage and Pronuclear-Stage Cryopreservation Results in High Delivery Rates in Fresh and Frozen Cycles

Abstract

Purpose : Evaluate IVF-ET outcome data for a unique culture and cryopreservation strategy. Methods : Retrospective study of 92 patients. Embryos for day-3 transfer were selected at pronuclear-stage; all extra zygotes were cryopreserved at pronuclear-stage. Results : Delivery rates for Anonymous Oocyte Donation (Group I), patients <35 years (Group II), and 35-38 years (Group III) were 52.9%, 61.5%, and 51.7% for fresh and 38.5%, 33.3%, and 40.0% for frozen transfer. Deliveries per retrieval were 82.3%, 71.8%, and 58.6%. Only 0.88, 0.80, and 0.61 more zygotes were cultured than what were used for fresh transfer. Singleton, twin, and triplet rates were 64.6%, 31.2%, and 4.2% for fresh and 69.2%, 30.8%, and 0% for frozen. Conclusions : Selection of day-3 transfer embryos at the pronuclear-stage and cryopreservation of extra zygotes results in high delivery rates in fresh and frozen cycles. This approach optimizes deliveries per retrieval and provides many patients with more than one pregnancy per retrieval.

Frozen-thawed embryo transfer and live birth: Long-term follow-up after one oocyte retrieval

“…We found implantation was 22% per individual frozen embryo transfered. In contrast, aggregate implantation across eight published studies of pronuclear-stage freezing with cleavage-stage transfer in nondonor patients was 10%, 95% CI 9% to 11% (568 of 5,574) (7,10,11,13,16,18,19,22), ranging from 6% (16) to 21% (22). Another "parameter of excellence" is live birth per individual embryo transfered (23).…”