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.
A prospective randomized comparison of luteal phase versus concurrent follicular phase initiation of gonadotropin-releasing hormone agonist for in vitro fertilization.
To compare the effects of gonadotropin-releasing hormone agonist (GnRH-a) initiation either preceding or concurrent with controlled ovarian hyperstimulation (COH) in patients undergoing in vitro fertilization-embryo transfer (IVF-ET).
                Fifty-five patients were prospectively randomized to receive either GnRH-a on cycle day 21 before COH until ovarian suppression was achieved (group I) or GnRH-a concurrently with COH commencing on cycle day 3 (group II).
                Serum gonadotropin and ovarian steroid hormone levels, as well as fertilization, spontaneous abortion, and live birth rates.
                Twenty-six patients in group I and 29 patients in group II underwent COH for IVF-ET. Patients in group II had significantly higher serum luteinizing hormone, progesterone, and testosterone levels during stimulation with human menopausal gonadotropins (hMG) before oocyte retrieval (P < 0.05). Despite similar fertilization, biochemical, and clinical pregnancy rates, the spontaneous abortion rate was higher in group II (5/6) compared with group I (1/7) (P < 0.05). Thus, the live birth rate/retrieval for group I was 6 of 24 (25%) as compared with that of group II, which was 1 of 26 (3.8%) (P < 0.05).
                The initiation of GnRH-a in the follicular phase concurrently with hMG is associated with evidence of premature luteinization, hyperandrogenemia, and poorer pregnancy outcome compared with luteal phase administration of GnRH-a before hMG for IVF-ET.