[Letrozole versus gonadotropin-releasing hormone antagonist during luteal phase in the prevention of ovarian hyperstimulation syndrome: a randomized controlled trial].

To explore and compare the preventive effect of using letrozole and gonadotropin-releasing hormone (GnRH) antagonist during luteal phase of patients at high risk for ovarian hyperstimulation syndrome (OHSS). A total of 99 infertile women undergoing in vitro fertilization and embryo transfer or intracytoplasmic sperm injection with high risk for OHSS were enrolled in this randomized controlled trial.The letrozole group (51) received letrozole of 7.5 mg daily for 3 days;the GnRH antagonist group (48) were given cetrorelix of 0.25 mg subcutaneously daily for 3 days. Both groups received support therapy combined with embryo cryopreservation. The incidence of OHSS was surveyed. And the serum concentration of estradiol, LH and progesterone on days 3, 5 and 8 after oocytes retrieval were measured. There were no statistical differences in terms of baseline characteristics of patients and outcomes of controlled ovarian hyperstimulation between the two groups.The incidence of moderate and severe OHSS was found no significantly difference between letrozole group [11.8%(6/51)] and GnRH antagonist group [10.4%(5/48);0.05]. The estradiol concentration of the indicated days on days 3,5 and 8 after oocytes retrieval in letrozole group and GnRH antagonist group were (1 417±3 543) versus (15 210±9 921) pmol/L, (1 692±4 330) versus (18 680±11 567) pmol/L, (239±336) versus (3 582±5 427) pmol/L, respectively;compared with GnRH antagonist group, the estradiol level was significantly lower in the letrozole group (all 0.01). The luteinizing hormone level in the letrozole group were (0.46±0.40), (0.56±0.55)and (0.67±0.58) U/L on days 3,5 and 8 after oocytes retrieval, which were significantly higher than those of GnRH antagonist group [(0.28±0.28), (0.30±0.19) and (0.45±0.37) U/L, respectively; all 0.05]. There was no obvious differences on progesterone levels between letrozole group and GnRH antagonist group (all 0.05),and on days 8 after oocytes retrieval,the level of progesterone in each group were significantly lower than those on day 3 and 5 after oocytes retrieval (0.05). Letrozole has the same efficiency as GnRH antagonist for the prevention of OHSS, faster and cheaper to use, but its efficacy seems not to be related to the suppression of steroidogenic during the luteal phase.