Uterine preparation with estrogen for oocyte donation: assessing the effect of treatment duration on pregnancy rates.

ABSTRACT

OBJECTIVE: To assess the effect of the duration of uterine preparation with E2 on pregnancy rates (PRs) in oocyte donation. DESIGN: A retrospective study. SETTING: IVF-ET Unit, oocyte donation program. PATIENTS Four hundred eleven patients undergoing 865 ET cycles after oocyte donation. Uterine preparation consisted of 6 mg/d E2 valerate. The duration of treatment varied according to the availability of the oocytes for donation. Progesterone, 100 mg/d, was added upon oocyte retrieval. Patients were divided into seven groups according to the duration of uterine preparation with E2, in 5-day ranks. MAIN OUTCOME MEASURES: Pregnancy rates per ET according to the duration of uterine preparation. RESULTS: No differences were noted in the mean age, number of oocytes received, fertilization rates, or number of embryos transferred when comparing all groups. Pregnancy rates ranged from 19% to 27% for E2 treatment of 5 to 35 days. CONCLUSION: Endometrial preparation in anonymous oocyte donation programs is achieved with continuous administration of E2 until oocytes become available. Our results show that this treatment may be extended for as long as 5 weeks with no significant decrease in PRs.