GnRH antagonist-induced inhibition of the premature LH surge increases pregnancy rates in IUI-stimulated cycles. A prospective randomized trial

BACKGROUND: Our prospective randomized controlled trial was designed to assess whether the use of GnRH antagonists can improve the success rate of controlled ovarian stimulation (COS)/intrauterine insemination (IUI) treatments, via inhibition of the premature LH rise. METHODS: A total of 104 patients were randomly divided, using a randomization list, into two groups: in group A (n = 52), recombinant FSH (rFSH) was given with GnRH antagonist Cetrorelix, and in group B (n = 52), the patients received rFSH alone in a manner similar to that of group A. The primary outcome measure was clinical pregnancy rate per couple. RESULTS: The pregnancy rate per patient was 53.8% in group A and 30.8% in group B (P = 0.017). The rate of premature LH surge was 7% in group A and 35% in group B (P < 0.0001). A premature luteinization was observed in two cycles of 144 in group A (1.4%) and in 16 cycles of 154 in group B (10.4%) (P = 0.001). The mean values of LH and progesterone were significantly lower in patients receiving GnRH antagonist than in those who did not (3.3 +/- 3.3 mIU/ml in group A versus 9.9 +/- 7.9 mIU/ml in group B, P < 0.0001, for LH; 1.3 +/- 1.1ng/ml versus 2.1 +/- 1.9ng/ml for group A and B, respectively, P < 0.0001, for progesterone). CONCLUSION: The use of GnRH antagonist in COS/IUI cycles improves pregnancy rate, preventing the premature LH rise and luteinization.