Gonadotropin-releasing hormone agonist (GNRH-A) triggering may improve live birth rates and reduce ovarian hyperstimulation syndrome (OHSS) in 'freeze-all' cycles: Time to re-think conventional triggering?.

OBJECTIVE: Many in vitro fertilisation (IVF) clinics worldwide preferentially use elective embryo cryopreservation. This study compares GnRHa triggering in 'freeze-all' cycles with conventional human chorionic gonadotropin (hCG) triggering for live birth rates (LBR), neonatal outcomes and OHSS incidence. DESIGN: A multi-centre, retrospective cohort study was performed for matched autologous and donor cycles. MATERIALS AND METHODS: 467 autologous and 111 donor cycles utilised a GnRHa trigger and 'freeze-all' approach from January 2012 to July 2015. Cycles were matched at a 1:1 ratio with hCG triggered 'freezeall' cycles. Cycles were matched for age, body mass index, polycystic ovarian syndrome (PCOS), stimulation cycle number and starting gonadotropin dose. Cycles were sub-stratified for OHSS risk, according to the presence of PCOS and/or recruitment of >14 follicles at ovulation. LBR was recorded for the first blastocyst transfer, cumulative LBR included all subsequent transfers. Fisher's or Chi-squared tests were performed for categorical data. Continuous data was non-parametrically distributed and Mann-Whitney testing was performed. P-values <0.05 were considered statistically significant. RESULT(S): In high-risk autologous cycles, LBR was 41.3% vs 31.7% after GnRHa and hCG triggering (p=0.08). Cumulative LBR was 58.1% vs 50.7% (p=0.16), with no difference in the number of embryos transferred. A similar trend in LBR was observed in low-risk women (GnRHa 45.5% vs hCG 29.2%, p=0.19). The incidence of OHSS was significantly lower in highrisk women (GnRHa 1.2% vs hCG 10.6%; OR 0.10 (0.03-0.29); p<0.05). No cases of OHSS were reported in low-risk women. In high-risk donor cycles, LBR was 40.1% vs 41.4% after GnRHa and hCG triggering (p=0.97). Cumulative LBR was 61.2% vs 54.8% (p=0.53) in highrisk women, and 56.5% vs 42.3% (p=0.16) in low-risk women. The incidence ofOHSS was 1.8%vs 3.9%(p=0.61) afterGnRHa and hCGtriggering in highrisk women, and 0% vs 1.7% in low-risk w