[Endometrial changes caused by induction of ovarian hyperstimulation which affect the process of embryo implantation].

In a natural process, the endometrium in under strict hormonal control. The protocols of multiple follicular growth produce estradiol supraphysiological concentrations (E2) that alter the progesterone/estradiol ratio (P4/E2), with concomitant diminution of endometrial receptivity; this could explain the low efficiency with assisted reproduction methods.