GnRH agonist versus GnRH antagonist in ovarian stimulation: the role of elevated peak serum progesterone levels.

Aim: We sought to evaluate the influence of subtle serum progesterone elevation on in vitro fertilization (IVF) cycle outcome and to assess the impact of the type of gonadotropin-releasing hormone (GnRH)-analogue used during controlled ovarian hyperstimulation (COH) on the probability of clinical pregnancy.
Patients and Methods: We reviewed the files of all consecutive patients undergoing COH with either GnRH-agonist or antagonist in our IVF unit during a 10-year period and who had their peak serum progesterone levels determined on the day of human chorionic gonadotropin (hCG) administration.
Results: Of the 2244 IVF cycles evaluated, 2103 had peak progesterone level of <1.5 ng/mL (normal-P group) and 141 of >1.5 ng/mL (high-P group) (6.28% of all the study population). Clinical pregnancy rate was significantly higher in the normal-P group (25.4% versus 16.6%; p < 0.006). Moreover, among the high-P group patients, the use of the long GnRH-agonist suppressive protocol (GnRH-ag) was more prevalent in patients who conceived as compared to those who did not (60.9% versus 39%, respectively; p < 0.05), with a tendency toward an increase pregnancy rate in those using GnRH-ag compared with GnRH-antagonist protocol (GnRH-antag; p < 0.059) COH protocols.
Conclusion: While subtle progesterone elevation in patients undergoing COH using GnRH-antag COH protocols, should dictate embryo cryopreservation and cancelation of the fresh transfer, in those undergoing the GnRH-ag COH protocol, a fresh embryo transfer should be recommended.