The chance of pregnancy in humans depends on many factors. One of the most important factors in predicting pregnancy outcome is embryo quality. There have been numerous strategies to promote development of human embryos in vitro including improved culture media, assisted hatching and co-culture techniques. Co-culturing provides a favourable environment for the embryos that does not hinder their development. We offer a co-culture system utilizing the patient's own endometrial (uterine lining) cells. A biopsy of the endometrium is obtained from the patient in a non-medicated cycle prior to an IVF attempt. These cells are prepared in the laboratory and then frozen for future use. At the time of the IVF trial the endometrial cells are thawed and cultured in small dishes. The fertilized eggs are placed on top of the cell layer and allowed to develop until the time of transfer.