INTRODUCTION
Gonadotropin releasing hormone (GnRH) analogues are essential in IVF to prevent a premature LH surge1-4. Inadequate suppression can cause early ovulation and affect oocyte quality and embryo development resulting in a low pregnancy rate5 6. Despite their overall effectiveness, GnRH analogues are associated with insufficient ovarian response and cycle cancellation in 5–20% of all IVF cycles7 8. Furthermore, GnRH analogues have been criticized as increasing IVF protocol complexity, resulting in increased costs and the need for an HCG trigger in GnRH agonist cycles, which increases the risk of ovarian hyperstimulation syndrome 9.
Concerning the adverse attributes of GnRH analogues, Kuang et al proposed the need for pituitary suppression methods that are more convenient, less costly and safer for patients. When given as cotreatment with exogenous gonadotropins for IVF, medroxyprogesterone acetate (MPA) was used in place of GnRH analogues to block the LH surge10. Prior studies indicate that compared with GnRH analogues, the use of MPA results in effective pituitary suppression with similar outcomes such as cycle cancellation rates, oocyte number and quality, fertilization rate, cleavage rate, blastocyst quality and pregnancy11. Because of the adverse effects of premature progesterone exposure on the endometrium, however, progestin cycles require a freeze-all IVF cycle with subsequent frozen embryo transfer (FET). Additionally, progestin cycles have been shown to require more gonadotropins compared with short GnRH agonist cycles . Several investigators have claimed that progestin cycles are more patient friendly and cost-effective11-17.
Progestins seem to provide higher pregnancy rates than the short GnRH agonist protocol following cryopreserved embryo transfers10 11 15. However, in most trials, the efficacy and reproductive outcomes of PPOS regimen were compared to short GnRH agonist protocol, which is now rarely used in many assisted reproduction programs and also the live birth rate were reported by per embryo transfer rather than cumulative live birth rates (CLBRs) which can reflect the real efficacy of ovarian stimulation in ART 18-21. Since many women with normal ovarian reserve are suitable for fresh embryo transfer in long agonist protocols, whether this would be the case compared with the more common long GnRH agonist protocol in which fresh transfer can be accomplished in the majority cases.
Therefore, the aim of the present study was to compare cumulative live birth rates and time to live birth in women with normal ovarian reserve following progestin primed ovarian stimulation protocol with long GnRH agonist protocol.