Topics related to ART and IVF is clouded by confusion and suspicion. There are many terminologies which are misunderstood and debated. One topic which keeps surfacing in such debates is the efficiency of frozen embryos for successful pregnancy. Success of frozen embryo transfer (FET) has increased dramatically over the last decade. In fact, the latest statistics show that frozen embryo transfer showed improved results in comparison to fresh embryo, especially in women over the age of 35.
Benefits of Frozen Embryo transfer
- The advantage of many cycles: As opposed to fresh embryo transfer, in FET availability of frozen embryos offers a chance to repeat the cycle without embarking on the ordeal of egg retrieval. Also, the advancements in cryopreservation techniques, especially vetrification, has improved the success rate of live birth from a single frozen embryo.
- Easier procedure: Procedure of FET is not simple but also not as time consuming as fresh embryo transfer. Surgery for egg retrieval is not necessary. In the beginning of the cycle, the uterine lining is prepared for an imminent implantation through the administration of estrogen injections. It is now understood that an increase in progesterone levels during ovarian stimulation (as in the case of fresh embryo transfer) reduces the receptivity of the endometrium for implantation. When levels of progesterone increases beyond the maximum permissible limit, all available embryos are frozen instead of proceeding with fresh embryo transfer. FET is a superior choice over fresh embryo transfer as it doesn’t demand an initial stimulation process. Women who chose ‘freeze all’ embryo approach showed maximum live births.
- Frozen embryos are genetically healthy: Genetic testing on frozen embryos reveals the presence of any genetic disorders. The procedure PGD (preimplantation genetic diagnosis) helps couples from passing on genetic disorders to their off spring. After the egg is retrieved and fertilized, an embryologist tests a biopsy for genetic disorders before freezing. Only those embryos which are free of genetic disorders are implanted.
Research assets superior efficiency of FET over fresh embryo transfer
Numerous studies have been performed in women who have undergone vigorous ovarian stimulation. Such participants are considered to be at a high risk for OHSS (ovarian hyperstimulation syndrome). In such cases, the attending physician decided to freeze the embryo instead of transferring it. For another group of OSHH women, the embryo was transferred. On comparing the success rates of both groups, it was found that the group which had their embryos frozen showed increased IVF success rate as compared to the other group of fresh embryo transfer. Conclusion drawn from this study was that it wasn’t the process of cryopreservation which influences success, but the quality of embryos available.
Frozen embryos remain viable for longer periods without compromising fertility.
Frozen embryo transfer is preferred by many women for they find the procedure less stressful than fresh embryo transfer. FET offers high success rate, in fact the statistics promised are the same as when the embryo is first frozen.