An egg has to become mature first before it can be fertilized. Occasionally, some collected eggs are not yet mature so at the lab the egg is injected with small amounts of hormone and placed in an incubator for maturation. When the eggs are mature, they are fertilized by intracytoplasmic sperm injection for a successful fertilization. Embryos are then cultured for three to five days before being transferred back to the mother’s womb. In vitro maturation increases the chances of egg and sperm meeting. It allows a woman to use some of her immature eggs and only the highest quality embryos are selected for implantation.