Frozen-thawed cycles significantly reduce pregnancy, live birth rates
MedWire News: Women who undergo oocyte slow-cooling preservation are significantly less likely to have a live birth after IVF than those undergoing treatment using fresh oocytes, suggest Italian study findings.
Andrea Borini (Tecnobios Procreazione, Bologna) and co-authors analyzed data from eight centers involving 2,046 patients, who underwent 2,209 oocyte retrievals for IVF treatment. The mean patient age at retrieval was 35 years.
On average, 12.9 oocytes were retrieved and 2.9 oocytes inseminated per cycle.
Among the 940 thawed-oocyte cycles, the oocyte survival rate was 55.8 percent, and fertilization rates and the mean numbers of inseminated oocytes were significantly reduced compared with after fresh cycles, at 72.5 versus 78.3 percent and 2.6 versus 2.9 oocytes, respectively.
Furthermore, thawed-oocyte cycles were associated with significantly lower rates of implantation (10.1 vs 15.4 percent), pregnancy rates per embryo transfer (17.0 vs 27.9 percent), and pregnancy rates per cycle (13.7 vs 26.2 percent) compared with fresh cycles. Overall, live birth rates were significantly higher in fresh cycles compared with thawed cycles, at 77.5 versus 68.2 percent.
Although most clinics achieved a pregnancy rate per thawing cycle above 14%, significant differences in clinical outcome were found among centers.
"Nevertheless, in cases of inapplicability of embryo cryopreservation, oocyte cryopreservation should be offered to patients with surplus oocytes," conclude Borini and team.
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By Ingrid Grasmo