Estradiol and progesterone replacement regimens for the induction of endometrial receptivity.

Initiation of pregnancy in premature ovarian failure patients by use of donated oocytes fertilized in vitro requires establishment of a normal endometrial environment. We compared administration of estradiol (E2) and progesterone (P) by polysiloxane vaginal rings versus oral micronized E2 and P vaginal suppositories in 10 such patients. Serum E2 levels were similar between groups and similar to normally-cycling controls. With vaginal administration of E2, a burst effect was noted, with marked elevation 1 hour after insertion. The pattern with oral administration was more consistent, although marked conversion to estrone occurred. The P cylinder and suppositories delivered similar levels, with diminution of P in some patients with the cylinder. Despite apparent limitations, endometrial histology was normal after each cycle; both groups achieved pregnancies. Administration of E2 and P by polysiloxane vaginal rings achieved hormonal levels similar to oral micronized E2 and P vaginal suppositories. Endometrial biopsies after the stimulated cycle were appropriately mature.