Therapeutic maturation of endometrium in in vitro fertilization and embryo transfer

Objective: To provide an up-to-date review of studies that have examined the relative role of endometrial development in in vitro fertilization (IVF) and embryo transfer (ET) treatment in relation to the treatment outcome. Data Identification: The most important published studies and personal communications related to this topic have been identified through a computerized bibliographical search (MEDLINE). Study Selection: Studies that have evaluated the endometrial maturation in IVF and ET treatment with respect to different treatment protocols of ovarian stimulation. Clinical trials exploring the efficacy of various combinations of hormonal supplementation that aim to improve the endometrial environment and treatment outcome. Publications and personal communications reporting a variety of treatment protocols and drugs utilized for the creation of artificial endometrial cycles in IVF treatment employing donated eggs. Results: Ovarian stimulation frequently adversely affects the process of endometrial maturation. Various kinds of hormonal supplementation, used in clomiphene citrate- and/or human menopausal gonadotropin (hMG)-stimulated cycles have not improved treatment outcome. Human chorionic gonadotropin or natural progesterone (P) supplementation administered after controlled ovarian stimulation with gonadotropin-releasing hormone and hMG effectively corrected the luteal phase defect and resulted in an improved conception rate. The endometrium of agonadal women is highly conducive to hormonal manipulation. All estrogen preparations used effectively promoted endometrial growth and proliferation. Natural P is superior to synthetic progestins for induction of receptive secretory endometrium. Conclusion: The development of adequately receptive endometrium is a major factor determining the outcome of IVF and ET treatment.