Embryo Freezing
Embryo freezing is commonly used to preserve embryos that have been
produced, but that are not transferred to the uterus. To date, over
150,000 births have occurred from the transfer of previously frozen
embryos, some having been frozen for more than a decade. Embryos are
frozen using a computer-guided process resulting in a final temperature
of -1960C. At this temperature the embryo ceases all
metabolic activity until thawed. The thawing process, however, can lead
to trauma and damage of the embryos, leading to a loss of viability. In
general, the implantation rates of previously frozen embryos are
approximately fifty percent that of fresh, never-frozen embryos.
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