The first baby following embryo cryopreservation was born in 1984. In 2010 a baby was born from an embryo that had been frozen for 20 years. The methods used to cryopreserve embryos have changed over time and are now highly successful and a routine part of the IVF process. The RMSCVA Laboratory uses a rapid-cooling method called “vitrification” to cryopreserve embryos. This method avoids the formation of damaging ice crystals and results in close to 100% survival after thawing.
At RMSCVA the majority of patients going through the IVF process will have embryos cryopreserved (frozen) 5 to 6 days after fertilization at the blastocyst stage of embryo development. There are various reasons for cryopreserving embryos during an IVF attempt:
- When using a “freeze all embryos” strategy, all suitable blastocyst-stage embryos are cryopreserved and none are transferred fresh. This allows the best embryo(s) from a retrieval to be thawed at a later date and transferred into a uterus that may be more “receptive” to the embryos than a uterus that has just been exposed to the medications needed to stimulate the ovaries for an IVF cycle. At RMSCVA we have seen high pregnancy rates using this strategy.
- When patients are undergoing preimplantation genetic testing for aneuploidy (PGT-A) or monogenetic diseases (PGT-M). A biopsy of the embryo is taken 5 to 6 days after fertilization and the embryo is cryopreserved while awaiting the genetic testing results.
- When patients are facing a medical treatment such as radiation or chemotherapy for cancer that may impact their future fertility, embryo cryopreservation is a way to preserve their fertility. For women without a male partner facing similar treatment, cryopreservation of unfertilized eggs is also an option
- When patients have excess blastocyst stage embryos following a fresh transfer IVF attempt.
Importantly, one advantage to embryo cryopreservation is that the embryos do not age while frozen. The chance of pregnancy remains the same as the pregnancy rate associated with the age of the woman when she did her IVF cycle.
The cryopreserved embryos are stored in liquid nitrogen tanks on-site at the RMSCVA Laboratory. Only RMSCVA Laboratory staff and physicians have access to these tanks and each tank is monitored 24/7 to ensure adequate storage conditions.
When necessary, cryopreserved embryos can be safely shipped to and received from other accredited laboratories.