One stimulation cycle can lead to the ripening of 5-15 eggs. However, only two (in some cases three) embryos are transferred into the uterine cavity. The remaining eggs in the pronculear stage can be frozen in liquid nitrogen (cryopreservation) and are then ready for embryo transfer in a later cycle. This means repeated stimulation with hormone injections and follicular puncture can be avoided for one or more cycles.
Cryopreservation is the freezing of (fertilised or unfertilised) eggs or embryos for use at a later point.
In legal terms, fertilised eggs and embryos are the future children of both partners. This means that both partners must always agree on their thawing and transfer.