GnRH antagonists: do they open new pathways to safer treatment in assisted reproductive techniques?

GnRH antagonists (GnRHnt) induce a rapid decrease in LH and FSH, preventing and interrupting LH surges. Their properties do not require a desensitization period and allow their use in the late follicular phase. GnRHnt could replace GnRH agonists (GnRHa) in ovarian stimulation without their side-effects and their long period of desensitivity. Both protocols using GnRHnt were associated with a smaller amount of gonadotrophin, a shorter stimulation period and a lower incidence of ovarian hyperstimulation syndrome (OHSS) with statistically comparable pregnancy rates. There is room for improvement of both protocols concerning the programming, the antagonist dose and the timing of antagonist administration. Luteal support should be maintained until the results of further studies. The perinatal outcome appears to be similar to that of other stimulation regimens. Triggering of ovulation can be facilitated by GnRHa for patients at risk of OHSS. Provided that pregnancy rates equivalent to those obtained with GnRHa are confirmed in larger series, GnRHnt will clearly represent a safer alternative to GnRHa protocols in IVF.