The whole procedure has several phases. In the first phase, the hormonal preparation is important; the goal of this phase is to mature larger quantity of eggs. Then, in the second phase, which is the transfer of eggs from ovaries to a special cultivation medium, sperms are transferred there as well. The third phase is a process of fertilization in which the cultivation takes place. At this stage, the whole process has a natural course without outside intervention. Fertilized eggs (embryos) are then transferred back to the patient's uterus.