title: Frozen-thawed transfer cycles: are they comparable with fresh?
abstract: 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.
authors.affiliation: Human Assisted Reproduction Ireland, Rotunda Hospital, Dublin. emocanu@rcsi.ie
authors.forename: E V
authors.initials: EV
authors.lastname: Mocanu
authors.forename: E
authors.initials: E
authors.lastname: Cottell
authors.forename: K
authors.initials: K
authors.lastname: Waite
authors.forename: B
authors.initials: B
authors.lastname: Hennelly
authors.forename: C
authors.initials: C
authors.lastname: Collins
authors.forename: R F
authors.initials: RF
authors.lastname: Harrison
mesh_terms: D015925:Cryopreservation; D010064:Embryo Implantation; D004624:Embryo Transfer; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D007247:Infertility, Female; D011247:Pregnancy; D018873:Pregnancy Rate / Q000639:trends*; D011272:Pregnancy, Multiple / Q000706:statistics & numerical data; D027724:Reproductive Techniques, Assisted; D015053:Zygote