Effect of estradiol levels after hCG trigger on embryo quality, implantation, and IVF outcome, using donor ovarian stimulation protocols

In this study, we aimed at delineating the possible effect of estradiol (E2) levels on the day of β-hCG administration on the ovary by analysingthe Embryo Score (ES) of early day 2, 44hrs post insemination. Oocyte donor ovarian stimulation protocols were thus used in order to avoid any possible counteractions of E2 with the endometrium. All oocytes were microinjected and all embryo transfers were fresh.E2 and E2/oocyte correlated positively with the ES on day 2 of embryo development. In contrast, the E2 and E2/oocyte do not appear to significantly affect the implantation and clinical pregnancy rates. Furthermore, E2 levels on the day of β-hCG administration were positively associated with fast and slowly dividing embryos compared to “ideally” dividing embryos on day 2. E2 levels corresponding to the “ideal” ES (E216) on day 2 sonographically translated into 12 mature oocytes. Embryos with “ideal” ES on day 2 were positively associated with implantation and gestational sac rates, as well as lower spontaneous miscarriage rates, in comparison to the fast and slowly dividing embryos. We propose that a) ES on day 2 of embryo development, 44hrs post insemination, is a valuable prognostic marker of embryo quality in ovarian stimulation protocols and b) an ovarian stimulation protocol may most likely be successful if not more than 12 oocytes are collected, i.e. E2 levels do not exceed 3.309pg/ml or on the day of hCG administration.