GnRH antagonists in ovarian stimulation: a treatment regimen of clinicians' second choice? Data from the German national IVF registry.

The place of GnRH antagonists in ovarian stimulation is controversial. Meta-analyses on studies comparing GnRH agonist and GnRH antagonist treatment regimens have suggested a comparatively lower efficacy of GnRH antagonists, which is likely to have influenced clinicians' attitudes. This report describes GnRH antagonist utilization for ovarian stimulation in Germany from 2000-2003. Data from the national IVF registry were analysed. The majority of ovarian stimulation cycles are still performed in long GnRH agonist protocols, although a significant increase in GnRH antagonist usage has been noted (P < 0.0001). Two observations support the notion that GnRH antagonists are often utilized as a treatment option in cycles with an unfavourable a priori prognosis: (i) the proportion of GnRH antagonist cycles increases with cycle rank (P < 0.0001, chi(2) for linear trend); and (ii) GnRH antagonist cycles are more often conducted in older patients as compared to GnRH agonist cycles (P < 0.0001). This has important implications for interpreting clinical performance of GnRH antagonists outside a research context.