Objective: Our purpose was to assess and clarify the mechanism of whether an early progesterone rise in cycles with gonadotropin-releasing hormone agonist (GnRH-a) is associated with an impairment of IVF outcome.
Methods: Seven hundred eighty-six cycles were induced with GnRH-a and human menopausal gonodotropin (hMG) ("long protocol"). Plasma progesterone (PP) levels on the day of human chorionic gonadotropin (hCG) administration were divided into three groups: < 0.9 ng/ml (Group A), 1-2 ng/ml (Group B), and > 2 ng/ml (Group C). We also analyzed the pregnancies achieved in our egg donation protocol in relation to the PP levels of each donor on the day of hCG administration.
Results: Group A involved 525 cycles, Group B had 223, and Group C had 38. The overall pregnancy rate per egg transfer was 19.2%, with the highest for Group A (22.3%), declining for Groups B (14.3%) and C (7.9%) (A = B = C; P < 0.005). The embryo implantation rate was found to be negatively correlated with the PP levels on the day of hCG administration. In contrast, there was an opposite trend between PP levels and the chance of conception in 30 pregnancies achieved by egg donation.
Conclusion: Since premature luteinization is very unlikely to occur under the conditions of this study, our findings suggest that an early PP rise has a negative impact on endometrial receptivity but not on egg and embryo quality.