The pregnancy rate was found to be higher when GnRHa was used in a long protocol as compared to a short or ultrashort protocol. There was no evidence of a difference in live birth rate, but this outcome was only reported by three studies. There was no evidence of a difference in the outcomes amongst various long protocols; nor that stopping or reducing GnRHa at the start of stimulation was associated with a reduced pregnancy rate. For all comparison, except a long versus short protocol, there was a lack of power.
The long protocol of administration of gonadotropin-releasing hormone agonist is superior to the short protocol for ovarian stimulation for in vitro fertilization.
To investigate whether pituitary desensitization with the gonadotropin-releasing hormone agonist (GnRH-a), buserelin acetate, before the administration of human menopausal gonadotropin (hMG) for ovarian stimulation in in vitro fertilization (IVF) is superior to the simultaneous administration of both hormones at the beginning of the treatment cycle.
                Prospective randomized study.
                Ninety-one patients having their first attempt at IVF.
                Patients in group 1 (long protocol) were administered subcutaneous (SC) buserelin acetate 200 micrograms/d from day 1 of the menstrual cycle, and hMG was started only after pituitary desensitization had been achieved at least 14 days later. Patients in group 2 (short protocol) were administered SC buserelin acetate 200 micrograms/d from day 2 and the same dose of hMG used in the long protocol from day 3 of the menstrual cycle.
                The median total amount of hMG required in both groups was comparable. There were significantly more follicles (P = 0.0001), oocytes (P = 0.0008), fertilized oocytes (P = 0.0001), and cleaved embryos (P = 0.0001), and a higher fertilization rate (P = 0.0047) in patients in group 1. The pregnancy rates per initiated cycle and per embryo transfer were 19.57% and 25.71% in group 1 compared with 8.89% and 16.67% in group 2.
                The long protocol is superior in terms of significantly greater follicular recruitment, oocyte recovery and fertilization rates, and significantly greater number of embryos available for transfer. In general, it is the preferred method when GnRH-a are used for ovarian stimulation in IVF.