Pretreatment of normal responders in fresh in vitro fertilization cycles: A comparison of transdermal estradiol and oral contraceptive pills

OBJECTIVE: The aim of this study was to investigate the impact of pretreatment with transdermal estradiol (E(2)) compared to oral contraceptive pills (OCPs) on controlled ovarian stimulation (COS) response in normal responders undergoing fresh in vitro fertilization (IVF)-embryo transfer (ET) cycles. METHODS: A retrospective cohort study was performed of normal responders undergoing fresh IVF-ET cycles who received pretreatment with transdermal E(2) versus OCPs prior to fresh IVF-ET. The total days of ovarian stimulation, total dosage of gonadotropins, total number of oocytes, and mature oocytes retrieved were noted. Pregnancy outcomes after ET were also recorded. RESULTS: A total of 2,092 patients met the inclusion criteria: 1,057 and 1,035 patients in the transdermal E(2) and OCP groups, respectively. Patients in the OCP group had a longer duration of COS (10.7±1.63 days, p<0.01) than the E(2) group (9.92±1.94 days). Patients in the OCP group also required higher cumulative doses of gonadotropins (2,657.3±1,187.9 IU) than those in the E(2) group (2,550.1±1,270.2 IU, p=0.002). No statistically significant differences were found in the total and mature oocytes retrieved or in the rates of biochemical pregnancy, clinical pregnancy, spontaneous miscarriage, and live birth between the groups. CONCLUSION: Our findings suggest that compared to OCPs, pretreatment with transdermal E(2) is associated with a shorter duration of ovarian stimulation and lower gonadotropin utilization, without compromising the oocyte yield or pregnancy outcomes in normal-responder patients undergoing fresh IVF.