For couples having trouble getting pregnant naturally, IVF is one of the most commonly recommended fertility treatments. In this treatment, the eggs and sperm are retrieved from the couple. The sperm is paired with the egg under clinical conditions for fertilization. Once it is fertilized, they will transfer the embryo to the woman’s uterus.
Now, if the embryo does not attach to the uterus, it will not result in a successful pregnancy and the couple can try again. Retrieving the sperm and eggs every time is not a feasible option for many. This is where frozen embryo transfer can help.
Frozen embryo transfer is a method of using previously frozen embryos instead of fresh embryos, for IVF. During a fresh IVF cycle, more than one egg can be fertilized by the sperm. In many cases, not all embryos will be transferred to the uterus for implantation. The remaining embryos can be preserved in a frozen state.
The number of embryos available for freezing will differ from couple to couple. The higher the woman’s age, the more the number of embryos transferred to the uterus to help increase the chances of successful implantation. Some couples may want to transfer just one embryo per cycle to avoid multiple births. In such cases, they can freeze the remaining embryos.
When the couple wants to go for another IVF attempt, they can use this frozen embryo. The fertility specialist will thaw the frozen embryo and transfer it back to the uterus. This frozen embryo can be from a previous IVF cycle where the woman’s eggs were used or it can be from a donor egg as well.
Embryos can be frozen only if they are of the required quality. Your fertility specialist will recommend freezing the embryos only if they are well-developed and healthy in the blastocyst stage.
The chances for such healthy embryos are high when the woman is below 35 years of age. The health of the eggs and the embryo decreases with age. The chances of having healthy embryos in this blastocyst stage are much lesser for a woman over 40 years when compared to someone in their early 30s.
The basic and the biggest question here is– on which day of the cycle is frozen embryo transfer done? The frozen embryo transfer implantation timeline will roughly be around 25 days.
During a FET, the uterus needs to be prepared for implantation. Hormonal injections and medicines are mostly given to ensure the endometrial lining is thick enough for an embryo transfer. In some cases, if the woman is young and healthy enough, the doctors can opt for a natural FET, where they allow the body to get ready on its own, without any external intervention.
Once the endometrial lining is thick enough, the FET is done in the next 5 days. The transfer day can vary from person to person based on various parameters. Therefore, for a FET, the timeline is longer than that of an IVF, because the uterus has to be rea died for a transfer. In an IVF, the eggs are retried, fertilized and transfer redback after 5 days. The uterus is readied before extracting the eggs itself.
Wondering what is the difference between a frozen and fresh embryo transfer?
In a fresh embryo transfer, the embryo is fresh – meaning the embryo was formed only then. The eggs were retrieved and fertilized using the male partner’s sperm and once a healthy embryo is for med, it is transferred back to the uterus. The eggs and sperm can be that of the couple or from donors, but the embryo formation is fresh.
In a frozen embryo transfer, an embryo that was for med in one of the previous IVF cycles and frozen under recommended conditions will be taken out, thawed and transferred back to the uterus. This frozen embryo can be many years old too.
Both methods have their advantages and disadvantages. The best person to talk to would be your fertility specialist, who will recommend the best course of treatment after considering all your options, issues and feasibility.
FET goes a step further than IVF by helping couples preserve their embryos from a single cycle, for years. Not all IVF treatments succeed on the first attempt and many couples go for multiple attempts. This can be financially and emotionally draining on one or both partners. Here are some reasons to consider FET or why FET is preferred:
· Chemotherapy – Chemotherapy can destroy the sperm or eggs and make it difficult for natural conception post-chemotherapy. However, one can freeze their eggs or sperm before starting chemo, there is no guarantee that a healthy embryo will form. If one or more embryos are already preserved, it increases the chances of a successful pregnancy.
· Medications – Certain medications can affect a person’s fertility. FET can be very beneficial when such medications become a necessity and cannot be avoided.
· Genetic Disorders – Some genetic disorders can affect the reproductive organs or the process itself. Preserving one or more embryos when both partners are in good health can reduce the chances of such disorders.
· Age – The chances of successful pregnancies decrease as the woman’s age increases. However, there will be risks for an older woman, the risk of no eggs or embryos due to the age factor is removed with the help of FET. A couple can decide to freeze their embryos when they are young and healthy and use them many years later, thus reducing many risks associated with age.
· Genetic Testing – Frozen embryo transfer allows genetic testing. If there is a history of genetic disorders in the family and a couple wants to ensure it is not passed on to the next generation, they can opt for Preimplantation Genetic Diagnosis (PGD) and Preimplantation Genetic Screening (PGS). These tests help the doctor identify and implant only the embryo that is healthy and free of any genetic issues or flaws.
· Same-Sex – When both partners belong to the same gender, they can use a donor egg, a donor sperm or both and freeze the embryos. This ensures their kids all have the same genetic makeup.
Considering the major benefits of a frozen embryo transfer &FET success rates, if you are opting for IVF and have many healthy embryos after taking a few of them for implantation, your fertility specialist might recommend freezing the rest for later use. You can always opt to not use it in the future but if you do freeze it, you have a backup option if needed.