ReviewGonadotropin-releasing hormone agonist (GnRHa) trigger - State of the art

GnRH agonist (GnRHa) trigger for final oocyte maturation in GnRH antagonist co-treated IVF/ICSI cycles significantly reduces the risk of ovarian hyperstimulation syndrome (OHSS). GnRHa trigger followed by modifications of the standard luteal phase support (modified luteal phase support) secures fresh transfer in the majority of patients with excellent reproductive outcomes. In freeze all cycles (segmented cycles) GnRHa trigger allows oocyte retrieval with a minimal risk of early onset OHSS and good reproductive outcomes in subsequent frozen thaw cycles. Overall, two different luteal phase support strategies have been proposed when a fresh transfer is performed after GnRHa trigger. These involve either boosting the endogenous steroid production or adding exogenous steroids. The present review discusses the advancement of GnRHa trigger in fresh and segmented cycles and how a modified luteal phase support policy in fresh transfer cycles results in good reproductive outcomes as well as a high safety in terms of OHSS reduction. Finally, the new concept of an individualized luteal phase support policy taking the number of pre-ovulatory follicles into account when planning a fresh transfer in GnRHa triggered IVF/ICSI cycle is discussed.