A common question asked by patients who plan to freeze embryos from their IVF treatment is, "How long do frozen embryos remain viable?". There have been several reports of embryos frozen for many years that still produced a pregnancy.
In the medical literature, the longest reported time for an embryo to be frozen, thawed and result in a viable healthy delivery was twelve years.
This is of special importance since some countries have passed legislation requiring embryos to be destroyed if not used after two to five years.
Researchers from New Jersey recently studied pregnancy rates using frozen embryos that had been frozen for varying lengths of time. The results are as follows:
|Number of cases attempted||32||54||50||23||20||3|
|Percentage of viable pregnancies or deliveries||28.1||35.2||36||60.9||30||66.7|
This data supports long term viability of frozen embryos. Couples can be reassured that frozen embryos remain viable for long periods of time. this enables who acheive pregnancy on their initial IVF attempt to freeze embryos and keep them stored until after they deliver and are ready to have additional children.