L26/P-351 Does GnRH agonist pre-treatment after freeze all strategy improve IVF/ICSI outcomes

Abstract Study question Is to compare the livebirth rate in deep endometriosis patients after freeze all strategy with or without Gonadotropin-Releasing Hormone agonist (GnRH-a) pretreatment. Summary answer The livebirth rate is higher in GnRH-a pretreatment group than without 32%vs 16% p = 0,23 furthermore the miscarriage rate is significantly lower 14,3%vs 71,4%p=0.006 What is known already The correlation of endometriosis patients and infertility is well established. one of the treatments of infertility associated to endometriosis is IVF-ICSI, however it has been shown that IVF -ICSI outcomes are worsened in endometriosis patients mainly in advanced stages comparing to those with tubalfactors or unexplained infertility: low oocytes low implantation rate low pregnancy rate are observed. GnRH-a isfrequently used prior IVF ICSI procedures in endometriosis patients, it has been suggested that this would improve pregnancy outcomes nevertheless this finding was for fresh embryo transfer regardless to the stage. controversy latest studies did not confirm these results. Study design, size, duration Prospective, randomized, open-label trail. Sixty-two patients with deep endometriosis and infertility were included. From 2019 and still ongoing Participants/materials, setting, methods Block randomization (block size 6) was used. Patients were divided into two groups: group 1 (n = 25) without pretreatment, group 2 (n = 37) three months of GnRH-a pretreatment. Antagonist protocol, estradiol priming, GnRH-a trigger, ICSI, and freeze-all embryos at blastocyst stage for all patients. Single embryo transfer was performed three months later; endometrium prepared in artificial cycle. Primary endpoint: live birth rate; secondary endpoint: miscarriage rate. This is an intermediate analysis with intention to treat. Main results and the role of chance The live birth rate was higher in group 2 treated with GnRH-a (32%; IC 95% 18–49.8) compared with group 1 without GnRH-a (16%; 95% IC 4.5–31.6). This difference indicates a potential but non-statistically significant relationship (Odds Ratio = 2.52; p = 0.23), suggesting a possible effect but also indicating that chance cannot be excluded, particularly due to the small sample size. In contrast, the miscarriage rate was significantly higher in group 1 without GnRH-a (71.4%) compared with group 2 with GnRH-a (14.3%), with an estimated Relative Risk of 5 and statistical significance (p = 0.006). Multivariable models adjusted for available covariates confirmed a protective effect of pretreatment against miscarriage and showed high discriminative performance (AUC > 0.80). Preliminary results suggest a potential benefit of pretreatment in reducing miscarriage risk and a trend toward improved live birth rates; however, confirmation in the final analysis is necessary. Limitations, reasons for caution Interim analysis with a limited sample size, reducing statistical power to detect differences in live birth rates. Risk of type I/II errors, wide confidence intervals. Preliminary results requiring confirmation in the final analysis. Wider implications of the findings These preliminary findings imply that patients with deep endometriosis may have a lower risk of miscarriage if they combine a freeze-all approach with extended GnRH agonist pretreatment. If confirmed, these findings could help guide reproductive management and support the need for larger, confirmatory trials. Trial registration number Yes