In a normal menstrual cycle, LH and FSH are the hormones that the body uses to stimulate development and maturation of a single oocyte. In order to optimize pregnancy rates during IVF, it is important to have more than one mature oocyte available for fertilization, embryo development and transfer into the uterus. The ovaries are therefore stimulated, using higher levels of the stimulating hormone that naturally exists in the body. (This is achieved using Gonadotrophin injections). Many different stimulation regimes exist at the moment, and the physician chooses the one best suited to the biological system of the particular patient, in order to achieve a good number of high quality oocytes. Close monitoring of the follicles (the sacs that contain the growing oocytes in the ovaries) is required and is achieved by ultra-sound, in order to determine their size and number. At the appropriate timing, an additional hormone will be administered that will aid with the final maturation of the oocytes. Based on all the available feedback and laboratory findings, the most suitable time for the recovery is determined. Alternatively, the Natural cycle-In Vitro Fertilization (NC-IVF) can be followed with the absence of hormone therapy where IVF is performed using the single follicle that grows naturally.