Initiation of GnRH antagonist on Day 1 of stimulation as compared to the long agonist protocol in PCOS patients. A randomized controlled trial: effect on hormonal levels and follicular development

BACKGROUND The optimal time for GnRH antagonist initiation is still debatable. The purpose of the current randomized controlled trial is to provide endocrine and follicular data during ovarian stimulation for IVF in patients with polycystic ovarian syndrome (PCOS) treated either with a long GnRH agonist scheme or a fixed day-1 GnRH antagonist protocol. METHODS Randomized patients in both groups (antagonist: n = 26; long agonist: n = 52) received oral contraceptive pill treatment for three weeks and a starting dose of 150 IU of follitropin beta. The primary outcome was E(2) level on Day 5 of stimulation, while secondary outcomes were follicular development, LH during ovarian stimulation and progesterone levels. RESULTS Significantly more follicles on days 5, 7 and 8 of stimulation, significantly higher estradiol (E(2)) levels on days 1, 3, 5, 7 and 8 and significantly higher progesterone levels on days 1, 5 and 8 of stimulation were observed in the antagonist when compared with the agonist group. E(2) was approximately twice as high in the antagonist when compared with the agonist group on day 5 of stimulation (432 versus 204 pg ml(-1), P lt; 0.001). These differences were accompanied by significantly lower LH levels on days 3 and 5 and significantly higher LH levels on days 1, 7 and 8 of stimulation in the antagonist when compared with the agonist group. CONCLUSIONS In PCOS patients undergoing IVF, initiation of GnRH antagonist concomitantly with recombinant FSH is associated with an earlier follicular growth and a different hormonal environment during the follicular phase when compared with the long agonist protocol.