First, eggs are retrieved from the ovaries, and then they are fertilized with the sperm sample provided. The fertilized eggs are then placed into an incubator for 5 days to grow into a mature embryo called a blastocyst. At this stage, the blastocyst can be transferred to the patient's uterus, or a gestational carrier, for implantation and potential pregnancy. The remaining blastocyst embryos, or all of the blastocyst embryos, can also be frozen at this point for future use.