If you are undergoing an IVF treatment, you are sure to have heard your doctor refer to the embryo transfer. They may choose to do it at the cleavage or blastocyst stages. Is blastocyst transfer recommended? Is it the right choice for your IVF cycle, or should you consider the cleavage stage?
During an IVF cycle, a fertility specialist extracts the eggs and sperm from both partners and puts them together in a lab dish for fertilisation or does icsi. Upon successful fertilisation, embryos form. These embryos continue to develop for the next 3 or 5 days before they are ready for implantation, which is known as embryo transfer.
Embryo transfer can happen on day 3 during the cleavage stage or on day 5 during the blastocyst stage. Both transfers have advantages and disadvantages. Doctors will recommend the type of transfer depending on various factors related to maternal age, history of pregnancy, past IVF cycle outcomes, genetic issues, and maternal health conditions.
There is no guarantee that either of the transfers will result in a successful pregnancy. The doctors recommend only the best option available to increase the chances of a successful pregnancy. The outcome of the transfer and the pregnancy depends on multiple factors and is unpredictable.
Blastocyst transfer is the process of transferring the embryo on day 5. By day 5, the embryos have developed enough and are ready to attach to the uterine wall. This stage of development is very similar to the natural development that happens inside the uterus. If there is an issue with the eggs or the sperm, the embryo may not survive until the blastocyst stage.
A blastocyst transfer happens 2 or 3 days later than a cleavage stage transfer. The collection and transfer procedures are the same for both types of transfers. The additional steps for a blastocyst embryo transfer are:
● Incubation – The embryos are kept in lab incubators until they reach the blastocyst stage.
● Blastocyst Grading—An embryologist uses the Grading System to grade the blastocysts based on three different parameters. Embryos with higher ratings have a better chance of positive pregnancy outcomes.
● Blastocyst Transfer—Unlike the cleavage-stage transfer, your doctor may transfer only one or two blastocysts and may recommend freezing the others for future use.
Blastocyst transfer is a technically advanced step in reproductive technology. It offers the following advantages:
● Higher Chances of Success
Over the years, records show that blastocyst embryo transfers have a higher success rate than cleavage-stage embryo transfers on day 3. Only a few embryos survive till day 5, and the strongest of these embryos are chosen for the blastocyst transfer.
● Choose the Best Embryos
Blastocyst embryo grading looks at various parameters of the embryos. The grading helps choose the best embryos for the transfer. The higher the embryo grading, the better its chances of converting into a successful pregnancy are.
● Genetic Testing
For couples where one or both partners or close family members have genetic issues, a blastocyst transfer facilitated PGT (preimplantation genetic testing). The fertility specialist will transfer the embryos without genetic or chromosomal abnormalities, thus reducing the risk of passing on the genetic issues.
● Low Risk of Multiple Births
The doctor will transfer only one or two viable embryos in a blastocyst embryo transfer. As the chances of positive outcomes are higher in this stage, doctors don’t feel the need to transfer multiple embryos to increase the chances of pregnancy. As a result, the risk of having multiple births is low.
Blastocyst Transfer Risks
Blastocyst transfer, though a very good option for IVF cycles, has a few risks too –
● Embryos Survival
Not all embryos can survive till the 5th day for a blastocyst transfer. The clinical conditions may not suit some embryos. As a result, you may only be left with a few viable embryos to choose from or freeze after the 5th day of transfer. In some cases, this could be the reason why the IVF fails – the lack of embryos to transfer.
● Damage During Thawing
The embryos are frozen on day 5. Some embryos may face damage during the freezing and thawing process.
Blastocyst transfer is a part of the IVF treatment. For couples who want to reduce the chances of multiple births, want to perform genetic testing on the embryos, increase their chances of a positive outcome, or have a history of multiple failed IVF cycles when embryo transfer was on day 3, a blastocyst transfer can be suitable.
Blastocyst transfer increases the chances of a successful pregnancy outcome. However, like any medical treatment, it has its own set of advantages and disadvantages. Talk to your fertility specialist, learn more about it, and make a well-informed decision.
● Yes, blastocyst transfer has a higher risk of ectopic pregnancy and preterm delivery. Not all embryos survive till this stage, reducing the availability of embryos for the transfer. It also increases the risk of gestational diabetes but has more positive outcomes than day 3 transfer.
● A blastocyst transfer is suitable for couples who want to reduce the chances of multiple births or want to do genetic testing to rule out the genetic transfer of some defective gene. It is also recommended when the couple has had multiple failed cycles, as blastocyst transfer increases the chances of a successful pregnancy.
● The embryologist grades the embryos on day 3 and day 5 based on various factors. They then choose the embryos with the highest gradings, as these have a higher chance of survival. They will transfer one or more of such embryos per the clinic’s protocols.
● Yes, you can. However, the general recommendation is to transfer only one blastocyst if you are under 37 years of age and a maximum of 2 if you are over 37 years. Since blastocysts have a higher rate of successful pregnancy, more than two transfers are not recommended for the health benefit of both mother and baby.
