Luteal phase characteristics following GnRH antagonist or agonist treatment – a comparative study

Due to inherent differences between gonadotrophin-releasing hormone (GnRH) antagonists and agonists, their late effect on ovarian steroidal production during the luteal phase of IVF cycles may differ. The aim of this study was to characterize and compare the luteal phase hormonal profile after the use of GnRH antagonists or agonists in ovarian stimulation protocols for IVF, in non-conception cycles, to avoid the effect of human chorionic gonadotrophin (HCG) during the luteal phase in conception cycles. Seventy-eight normo-ovulatory patients <35 years old, undergoing IVF due to male or tubal infertility were randomly allocated either to a GnRH antagonist (study group) or GnRH agonist treatment (control group). Similar standard luteal support was given to all patients, using vaginal micronized progesterone. In non-conception cycles, no statistically significant differences were found comparing luteal phase. oestradiol or progesterone levels in the study and control groups. No statistically significant differences were found comparing the hormonal profile dynamics, the mid-luteal (HCG day +8) oestradiol/progesterone ratio and the percentage of mid-luteal oestradiol decline between the study and control groups. In conclusion, similar characteristics and dynamics of luteal phase oestradiol and progesterone were demonstrated comparing ovarian stimulation for IVF using GnRH agonist or antagonists, under similar luteal support.