Use of steroid pre-treatments in IVF-ICSI cycles with GnRH antagonist protocol and their impact on gestational outcomes.

Different steroid pre-treatments have been used to schedule the start of the ovarian stimulation in IVF cycles. Currently, there is controversy about their effects on gestational outcomes. We designed a three-armed randomised controlled trial (RCT). Eighty-six normoresponder patients undergoing IVF treatment with antagonist GnRH protocol were allocated to three different groups. In the group 1, 34 patients received oral contraceptive pill (OCP) from the first day of the cycle to five days before starting ovarian stimulation, in the group 2, 25 patients received 2 mg/12 hours of oral E2 valerate from day 25 of the previous cycle until the day before starting stimulation, and finally, in the group 3, 27 patients did not receive any treatment. There are no statistically significant differences neither in clinical pregnancy rate (CPR) (40.9% OCP vs. 28.6% E2 vs. 53.3% no treatment group, =.388) nor live birth rate (LBR) (31.8% OCP vs. 28.6% E2 vs. 46.7% no treatment group, =.537) between groups in fresh embryo transfer. Likewise, no differences were found in the cumulative CPR, nor in cumulative LBR. However, there is a tendency to worst outcomes in the E2 group. In this E2 group, we observed better results with longer exposition, although no significant differences are reached (E2 mean days in the pregnant group 8.29 vs. 6.83 in the non-pregnant group, =.08). Our study shows no significant differences in pregnancy rates between groups, but the E2 group is trending at worse gestational results. Eudra-CT registration number is 2014-001809-40.Impact Statement Nowadays, there is much controversy about how pregnancy rates could be affected by the selection of steroid pre-treatments used in order to schedule IVF cycles. However, these treatments are widely utilised in clinical practice. The results support the clinical findings of most of the studies previously published. No significant differences in gestational outcomes were found between the groups treated with steroid pre-treatments and the control group. Additionally, oestrogen pre-treatment seems to be related to better pregnancy outcomes when the exposition is longer. Thus, an earlier start of this treatment in the luteal phase could be the optimal approach. This study pretends to provide clarity about the treatment guidelines of steroid pre-treatments to schedule the clinical work without impact on gestational outcomes.