Embryo freezing is a method of preserving embryos for future transfer. Embryos are cooled and then stored at an extremely low temperature. Embryos can later be thawed and transferred to the uterus. Embryo freezing can increase the options available to IVF couples. The ideal number of embryos to transfer during an IVF cycle is usually two or three. Some couples have more than this number. Embryo freezing provides a method of storing the extra embryos so they can be used at another time. If successful in producing a pregnancy, this may save the woman from having to go through ovulation stimulation, egg retrieval and the costs associated with an IVF cycle. If spare embryos are considered to be of good quality, they will not have to be discarded. They can be saved and used during a natural or medicated cycle at a later date. We usually recommend the addition of medication during such a cycle.