Implantation rates of euploid embryos are not influenced by the duration of estradiol priming, but the hormonal environment—estradiol and progesterone—may affect placentation

Implantation rates of euploid embryos are not influenced by the duration of estradiol priming, but the hormonal environment—estradiol and progesterone—may affect placentation
Quickly following in the footsteps of new assisted reproductive technologies (ART), the use of donor eggs (DE-ART) became available in the mid-eighties. Originally offered to women whose ovarian function had totally ceased, DE-ART taught us that the replacement of E2 and P sufficed for optimizing endometrial receptivity. Right from the inception, endometrial receptivity and pregnancy rates (PRs) in DE-ART surpassed or equaled PRs obtained in the same ART centers. The early days of DE-ART and attempts to facilitate the synchronization of donor and recipients taught us that there appeared to be great leeway in the duration of the necessary E2 priming phase, which could span from 10 to 100 days without affecting PRs (1).
Source: fertstert.org