Cumulative live birth rate in freeze-all cycles is comparable to that of a conventional embryo transfer policy at the cleavage stage but superior at the blastocyst stage
In a heterogeneous cohort of patients, the overall cumulative live birth rate of a freeze-all approach seems to prevail if embryo cryopreservation is carried out at the blastocyst stage.
Volume 110, Issue 4, Pages 703–709
Carlotta Zacà, B.Sc., Antonia Bazzocchi, M.D., Francesca Pennetta, B.Sc., Maria Antonietta Bonu, B.Sc., Giovanni Coticchio, Ph.D., Andrea Borini, M.D.
To determine whether the freeze-all policy ensures a higher efficacy in terms of cumulative live birth rate (CLBR) in comparison with a conventional fresh/frozen embryo transfer (ET) approach in patients with normal ovarian response.
Retrospective, matched, multicenter cohort study.
Private IVF centers.
This study analyzed 564 completed IVF cycles in which an average of 12–18 oocytes were retrieved. In 435 cycles the conventional strategy was applied, with initial ET followed by frozen embryo replacements, whereas in 129 cycles the freeze-all policy was performed, with elective cryopreservation and deferred use of all viable embryos.
Main Outcome Measure(s)
The primary endpoint was CLBR. The secondary endpoint was cumulative clinical pregnancy rate.
Overall, statistically comparable CLBRs were achieved in the fresh/frozen and freeze-all groups (45.5% vs. 53.5%). Stratification of data for age and number of retrieved oocytes confirmed the absence of differences between the two groups. In a subanalysis in which the day of ET and cryopreservation were taken into account, a similar outcome was achieved in cleavage-stage groups (45.6% vs. 46.4%), whereas when ET was performed at the blastocyst stage the CLBR was significantly higher in the freeze-all group (45.3% vs. 66.7%).
Our CLBR analysis indicates that clinical performance of the freeze-all policy is equivalent to that of the conventional strategy when ET is carried out at the cleavage stage. However, it seems to be superior if associated with cryopreservation and transfer at the blastocyst stage.