The influence of stimulation regimes and luteal phase support on the outcome of IVF.

Successful in-vitro fertilization (IVF) requires the generation of a number of healthy embryos and adequate priming and maintenance of a receptive endometrium. Both of these factors are influenced by ovarian stimulation regimes and are responsive to endocrine manipulation. Detailed analysis of follicular phase patterns of hormone secretion have established an inverse relationship between luteinizing hormone (LH) and egg/embryo quality which is not discernible on microscopic examination. The advent and extensive use of LHRH agonists in ovarian stimulation has gone some way towards optimizing embryo fitness by suppressing LH secretion and this has exposed the endometrial contribution to a failure of implantation to closer examination. The supraphysiological production of oestradiol and progesterone from the large numbers of follicles developed during ovarian stimulation cannot be without effect on the endometrium. Data presented in this brief review show how our understanding of ovarian stimulation and its influence on the outcomes of IVF has advanced and highlights the opportunities for manipulation of the endometrium to encourage implantation.