Impact of estradiol and progesterone levels during the late follicular stage on the outcome of GnRH antagonist protocols.

The study aimed to assess the impacts and the targets of progesterone (P4) and estradiol (E2) levels on IVF outcomes in GnRH antagonist protocols. The study was retrospective and concerned patients for their first fresh embryo transfers, after stimulation by a recombinant FSH (rFSH)-GnRH antagonist protocol, between September 2012 and July 2017 in the Toulouse University Hospital. Multivariable analysis, taking into account female age and the ovarian stimulation index, showed that E2 levels had no impact on IVF outcomes, while high P4 levels (>1.10 ng/mL) were associated to low pregnancy rate. The P4 concentrations were significantly negatively correlated to the percentage of top embryos and to the implantation rate. Therefore, the deleterious effect of high levels P4 could to act mainly by impairing embryo quality, which questions the place of the freeze-all strategy in these cases.