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

Objective To assess the effect of the duration of uterine preparation with E 2 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 6mg/d E 2 valerate. The duration of treatment varied according to the availability of the oocytes for donation. Progesterone, 100mg/d, was added upon oocyte retrieval. Patients were divided into seven groups according to the duration of uterine preparation with E 2 , 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 E 2 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.