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Cryopreservation, Embryo Implantation, Embryo Transfer, Female, Fertilization in Vitro, Humans, Infertility, Female, Pregnancy, Pregnancy Rate, Pregnancy, Multiple, Reproductive Techniques, Assisted, Zygote


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Cryopreservation of zygotes and subsequent thaw and transfer is an established ART treatment. We assessed if success rates frozen-thawed (day 2) zygotes are comparable with the outcome in fresh cycles of treatment. We performed a prospective follow-up and analysis of all frozen (FZT) and fresh cycles of treatment during a 12 months period. One hundred and nineteen patients in the frozen-thawed and 652 in the fresh group had a transfer. The overall thaw-survival rate was 71.7%. Clinical pregnancy rates per thaw and transfer were respectively 15.1% and 21% in the frozen and 29.1% (per transfer) in the fresh group. Implantation rates in fresh and frozen cycles were 16% and 12.3% respectively. The pregnancy loss rate was higher in the FZT group (29% vs. 18.3%). Cryopreservation of good quality zygotes, after fresh transfer offers optimal success rates in subsequent frozen treatment. It also encourages consideration of elective single zygote transfers.


Medicine and Health Sciences | Obstetrics and Gynecology


Mocanu EV, Cottell E, Waite K, Hennelly B, Collins C, Harrison RF. Frozen-thawed transfer cycles: are they comparable with fresh? Irish Medical Journal. 2008;101(6):181-4.

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