The effect of a prolonged artificial follicular phase on endometrial development in an oocyte donation program

Stretching the duration of an artificial follicular phase in an oocyte donation program facilitates greatly the synchronization between the donor and the recipient. In order to investigate the limits of such a prolonged endometrial preparation, 18 patients with ovarian failure were studied during 20 treatment cycles. These patients were prospectively and randomly divided into three groups (A, B, and C in eight, six, and six cycles respectively). All groups were treated with oral estradiol and estriol (at a 2:1 ratio), 4 mg/day for 21, 28, and 35 days, respectively. At this stage 50 mg/day of intramuscular progesterone was added for additional 7 days. Endometrial adequacy was evaluated by late follicular and midluteal endometrial biopsies. During treatment no patient suffered from breakthrough bleeding. The mean estradiol and progesterone levels during the follicular and luteal phases did not differ significantly between groups. All late follicular biopsies showed a normal proliferative endometrium with no signs of glandular cystic hyperplasia. The midluteal biopsy showed a secretory endometrium adequate for 18.6 +/- 1.8, 21.8 +/- 1.8, and 18.6 +/- 1.5 days in groups A, B, and C, respectively, with no significant glandular-stromal disparity. We conclude that an artificial prolonged follicular phase does not seem to affect adversely the endometrial preparation in an oocyte donation program.