Early GnRH antagonist initiation increase follicular synchronization and no. of mature oocyte

Recently, it has been suggested to initiate the GnRH antagonist use earlier than the established fixed GnRH antagonist regimen to achieve a more synchronized follicular growth and lower exposures to FSH, LH, estradiol and progesterone. The objective of this study was to assess the impact of IVF cycle using early initiation of GnRH antagonist on follicular synchronization and pregnancy outcome compared with those of GnRH antagonist fixed multi-dose protocol. Prospective. This study was designed prospectively from January 2011 to March 2012. For early GnRH antagonist initiation cycles (n=34cycles, 34patients), GnRH antagonist (Cetrorelix 0.25mg) was administered form the 2nd day of menstruation. As a control GnRH antagonist fixed multi-dose protocol cycles, GnRH antagonist administration form the day of leading follicle sized 12∼14mm, were included (n=34cycles, 34patients). For final oocyte maturation hCG was administered when the leading follicle sized 18mm. Primary outcome measures included No. of retrieved oocyte and mature oocyte, and secondary measure was pregnancy outcome such as clinical pregnancy rate (CPR). There were no differences in mean female patient's age (34.1 vs. 34.2 years), BMI (21.4 vs. 22.3) and basal FSH level (7.6 vs. 7.5 IU/ml) between study and control group.The men E2 level on hCG administration (3432.9 vs. 2533.6 pg/ml, NS) and No. of retrieved oocyte (14.4 vs. 11.4, NS) tended to be higher in study group. The No. of mature oocyte was significantly higher in study group than that of control group (11.9 vs. 8.2, P=0.04). The CPR per attempt cycle showed no difference between two groups (23.5% vs. 26.5%, NS). Early GnRH antagonist initiation increased follicular synchronization resulting in increase of No. of retrieved oocyte and No. of mature oocyte. However, further study might be necessary to evaluate the effect of GnRH antagonst longer administration on endometrial receptivity to increase CPR.