Programming in vitro fertilization retrievals during working days after a gonadotropin-releasing hormone antagonist protocol with estrogen pretreatment: does the length of exposure to estradiol impact on controlled ovarian hyperstimulation outcomes?

OBJECTIVE: To verify whether a variable number of days beyond the menses of estrogen (E) pretreatment may impact on controlled ovarian hyperstimulation (COH) outcomes and birth rate using a GnRH antagonist protocol.
DESIGN: Single center, prospective, nonrandomized study.
SETTING: Nonacademic fertility unit. PATIENT(S): A total of 1,080 women, aged 25-38 years, consecutively included (1,603 cycles). INTERVENTION(S): Given 4 mg/d E(2) valerate, started 3 days before the theoretical date of the next menses up to the first day of stimulation (S1). MAIN OUTCOME MEASURE(S): Hormone serum levels, drug exposure, and main IVF outcomes. RESULT(S): The cancellation rate was similar in the six similarly sized groups according to the number of days with E(2) pretreatment beyond the menses (1-8 days). The mean serum E(2) and LH levels at S1 gradually increased along with E(2) exposure, whereas the mean serum P level decreased. The mean serum E(2) level on the day of hCG administration gradually increased along with E(2) exposure. Serum LH level at S1 correlated significantly and positively to the length of E(2) exposure and to E(2) level on the day of hCG administration. No significant difference was observed for the number of oocytes retrieved and the number of embryos obtained. Women exposed the longest to exogenous E(2) tended to have higher pregnancy rates (PR). CONCLUSION(S): Extending E(2) pretreatment beyond the menses had no deleterious effect on the main COH outcomes and proved to be slightly beneficial.