Effect of reduced dose of triptorelin at the start of ovarian stimulation on the outcome of IVF: a randomized study

BACKGROUND: Partial pituitary desensitization using gonadotrophin-releasing hormone (GnRH) agonists may be sufficient in women undergoing controlled ovarian hyperstimulation for assisted reproduction. However, the minimal effective agonist dose remains to be determined. The aim of the study was to investigate the effect of a reduced daily dose of triptorelin, administered at the start of ovarian stimulation, on the results of IVF and intracytoplasmic sperm injection. METHODS: A total of 132 patients was randomized in two groups. Pituitary desensitization was obtained in group 1 (66 patients) with a single 3.75 mg injection (i.m.) of triptorelin. In group 2, 66 patients received 100 μg triptorelin daily, which was then reduced to 50 μg at the start of follicle-stimulating hormone (FSH) stimulation. RESULTS: No significant differences were found in terms of pregnancy rate per transfer (38% in group 1 versus 34.9% in group 2), implantation rate (20.2 versus 18%) and abortion rate (8.3 versus 9.1%). The number of FSH ampoules used, as well as the number of days stimulation required, was significantly reduced in group 2 (41 ± 26 versus 46.6 ± 25.3, P < 0.03 and 11 ± 1.3 versus 11.8 ± 1.5, P < 0.002 respectively). No significant differences were seen in oestradiol concentrations and in follicle number, in the quantity of oocytes collected and fertilized, or in the number of embryos obtained or transferred. CONCLUSION: A reduced dose of triptorelin is enough for pituitary suppression during ovarian stimulation but provides no significant improvement in IVF cycle outcome when compared with depot formulation. The possibility of a shorter treatment protocol requiring lower amounts of gonadotrophins should be considered in view of its economic advantage.