Often couples have excess embryos after an invitro fertilization (IVF) cycle that have been cryopreserved for future use.  Embryo cryopreservation is a routine practice within advanced reproductive technology (ART) clinics.   During a frozen embryo transfer cycle, the uterus is prepared with both estrogen and progesterone hormones to make the uterus receptive. This hormonal preparation typically takes 3-4 weeks of time.  During this 3-4 week time period, both hormone levels and the uterine lining are monitored to ensure optimal uterine receptivity.  Cryopreserved embryos are then thawed and transferred back into the uterus. Approximately 80% of embryos typically will survive the freeze-thaw process.  Embryos are dehydrated prior to freezing to minimize ice crystal formation in the embryo which causes intracellular damage.  Pregnancy testing typically occurs 8 and 10 days after the embryo transfer. If high quality embryo(s) are transferred, approximately 40% pregnancy rate is achieved per frozen embryo transfer.  Embryo cryopreservation techniques and capabilities have become an increasingly important therapeutic strategy in assisted reproduction.  About 20% of all offspring born worldwide from IVF cycles are from embryo cryopreservation and frozen embryo transfer procedures.