Effect of duration of estradiol replacement on the outcome of oocyte donation

To investigate if duration of estrogenic endometrial stimulation can affect recipient pregnancy rate in an ovum donation program.

Each recipient received micronized 17 beta-estradiol orally in a steadily increasing dosage from 2 to 6 mg daily over a period of time varying from 5 to 76 days until oocyte were available for donation. Recipients (520 patients for a total of 835 transfer cycles) were retrospectively divided into five groups depending on the duration of E2 administration.

No significant difference was seen in pregnancy and implantation rates between groups. There was a higher number of miscarriages in Group A (41%), p < 0.05 vs. Group B (15%), and vs. Group E (1%). Age, number of pregnancies and miscarriages, or implantation rate in donors (327 women aged < 35 years) were similar in all the five groups.

Endometrial receptivity is tolerant to a wide duration of E2 treatment (until 2 months), while waiting for oocytes available for donation, but best results are achieved with a treatment range of 11 to about 40 days.