Royal College of Surgeons in Ireland
Frozen-thawed transfer cycles: are they comparable with fresh?.pdf (213.7 kB)

Frozen-thawed transfer cycles: are they comparable with fresh?

Download (213.7 kB)
Version 2 2021-10-01, 16:36
Version 1 2019-11-22, 16:44
journal contribution
posted on 2021-10-01, 16:36 authored by Edgar MocanuEdgar Mocanu, Evelyn Cottell, K Waite, Bernadette Hennelly, Claire Collins, Robert F. Harrison

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.



The original article is available at

Published Citation

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.

Publication Date


PubMed ID



  • Obstetrics and Gynaecology