Background: The objective of this prospective study was to assess the impact of elevated serum progesterone levels on day 2 of the cycle on pregnancy rates in patients treated by IVF using GnRH antagonists.
Methods: Ovarian stimulation was started on day 2 of the cycle if progesterone levels were normal (normal-P group, n = 390). In the presence of elevated progesterone, initiation of stimulation was postponed for 1 or 2 days (high-P group, n = 20) and was started if repeat progesterone levels returned to normal range (n = 16). Stimulation was performed with recombinant FSH (rFSH) and GnRH antagonist was always started on day 6 of stimulation.
Results: A significantly higher exposure to progesterone and a significantly lower exposure to estradiol was present in the high-P as compared with the normal-P group from day 1 to day 8 of stimulation. In addition, a significantly lower ongoing pregnancy rate both per started cycle (5.0% versus 31.8%; P = 0.01) and per embryo transfer (6.3% versus 36.9%; P = 0.01) was present in the high-P compared with the normal-P group, respectively.
Conclusions: The presence of elevated serum progesterone on day 2 of the cycle is associated with a decreased chance of pregnancy in patients treated with rFSH and GnRH antagonists.