P-068 Real-world data shows that frozen-thawed ejaculates used for ICSI with autologous oocytes have lower but clinically negligible cumulative live birth rates compared to fresh samples
Authors: Hervas I , Gil Julià M , Cozzolino M , Navarro-Gomezlechon A , Mossetti L , Pacheco R , Rivera-Egea R , Garrido N 
Published: June 2023

Abstract

Study question
Does frozen-thawed sperm show an impact on success rates in ICSI with autologous oocyte cycles compared to fresh samples?

Summary answer
The slight decrease in cumulative live birth rates (CLBR) compared to using fresh samples should not overshadow the benefits offered by sperm freezing.

What is known already
Sperm freezing offers many advantages for cycle planning, logistics, sample safekeeping and patient comfort, becoming a reliable daily procedure in infertility clinics worldwide. Nevertheless, there is a lack of agreement amongst the published literature on the potential effect of using frozen-thawed sperm samples for ICSI cycles. The present study focused on outcomes of ICSI cycles using autologous oocytes and, in addition to expressing results as classical success rates, it assessed CLBR, which accounts for the contribution of all used oocytes and embryos from the same insemination procedure towards achieving a live birth.

Study design, size, duration
This is a retrospective multicenter observational cohort study involving 84,371 ICSI procedures with patients’ autologous oocytes (81,504 with fresh ejaculate semen samples and 2,856 with frozen ejaculate samples) from January 2008 to November 2021. The fresh sample group included real-world data from the clinical records of these patients and cycles from a cohort of 654,019 inseminated oocytes and 117,443 embryos transferred; whereas the frozen sample group considered 22,518 injected oocytes and 3,847 embryos replaced.

Participants/materials, setting, methods
Classical outcomes such as pregnancy rates and live birth rates (LBR) per embryo transfer (ET) were compared between the two study groups. Generalized linear models were used to obtain adjusted odds ratios (adjOR) and p-values for the comparisons. CLBR were expressed per ET, per embryo transferred and used oocyte, and were plotted as Kaplan-Meier curves. These were adjusted to the female patients’ age using Cox regression models to obtain adjusted hazard ratios and p-values.

Main results and the role of chance
There were statistically significant differences between both groups in terms of clinical and ongoing pregnancy rates per ET, and LBR per ET. However, after being adjusted to female and male patients’ age and BMI, total progressive motile sperm, semen capacitation, transfer before or at the blastocyst stage, and use of PGT, these differences were no longer statistically significant. Once three embryos were replaced, CLBR was 50.50% (49.91-51.08) in the fresh sample group, versus a 45.12% (41.77-48.28) in the frozen sample group. After five embryos transferred, these were 68.21% (67.27-69.13) and 64.62% (57.81-70.33) respectively (p &gt; 0.001). The Cox regression resulted in an adjusted hazard ratio (adjHR) of 1.166 (1.076-1.264). The CLBR in the fresh sample group was 33.15% (32.69-33.61) after using 10 oocytes and 49.93% (49.31-50.54) after 14. In the frozen sample group, these were 28.73% (26.24-31.13) and 43.13% (39.78-46.30) (p &gt; 0.001). The adjHR for this comparison was 1.220 (1.125-1.322).

Limitations, reasons for caution
The multivariate analyses aim to control to the best of our abilities the main limitation of the study, which is the potential biases that could be introduced due to the heterogeneity of the data and the retrospective nature of the present study.

Wider implications of the findings
Although frozen samples had slightly decreased CLBR per used oocyte and ET, there were no statistically significant differences in pregnancy and LBR per ET after the multivariate analysis. The extensive real-world data provided shows that slight declines in CLBR should not offset the many advantages that semen freezing offers.

Trial registration number
Not Applicable