In a single IVF cycle, a large number of embryos is sometimes produced. When transferring embryos back into the uterus we try to avoid multifetal pregnancy, and therefore more than 2 embryos are rarely transferred. Thus, at the end of a treatment cycle, extra embryos may be cryopreserved and used in the future in case the patient does not conceive or if she returns for treatment again after completing her pregnancy.

Embryos may be cryopreserved at different stages of division for an indefinite period of time.

A patient who's had embryos cryopreserved in a previous cycle may undergo a cycle of ovulation induction and embryo transfer without ovum pick up. Such a cycle may be easier than normal IVF cycles. The chances for multifetal pregnancy do not differ from those of a normal IVF cycle.