At each egg retrieval process, more than one egg is usually extracted; so that, more than one embryo can be produced in the laboratory. A number of resulting embryos are transferred to the uterus while the rest are frozen to be used in further IVF cycle if the first one is not successful.
Furthermore, these frozen embryos can be used in a case the couple wishes to have children again in the coming years. Although the chances of a successful pregnancy with frozen embryos are slightly lower; but, its lower cost and the reduced risks and complications of re-egg retrieval make this method a very good option.