Benefits and Drawbacks of Fresh vs Frozen Embryo Transfers
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Benefits and Drawbacks of Fresh vs Frozen Embryo Transfers

The family-building process is generally desired but not as straightforward as many think. Embryo transfer preparation for most couples can be filled with uncertainties and fear. This is especially so for couples that must have experienced multiple IVF failures in the past. They may also be worried about which type of transfer to use, whether they should transfer fresh embryos immediately or freeze the embryos and transfer them at a later date. In this article, the benefits and drawbacks of fresh vs frozen embryo transfers are discussed, and the process itself is also explained.

Benefits and Drawbacks of Fresh vs Frozen Embryo Transfers- image
Picture courtesy: ZIVA fertility center

What is Embryo Transfer?

Embryo transfer is the last and most important step of in vitro fertilization (IVF). It involves the transfer of embryos into the uterus of the woman that is undergoing IVF treatment. Both the fresh and frozen embryo transfers start with the same processes. The ovaries are first stimulated, and monitored, and the eggs are retrieved. After the retrieval, they are fertilized in the laboratory by sperm to create an embryo. After this is where the two processes start to differ. In a fresh embryo transfer, the fertilized embryo will be transferred into the uterus within 3-5 days after the egg retrieval. While in frozen embryo transfer, the embryos are frozen, with the transfer into the uterus taking place weeks, months, or even years after the egg retrieval and fertilization.

What is the technique of embryo transfer?

Embryo transfer involves the visualization of the cervix and the ultrasound-guided placing of the embryos into a precise location in the uterus. The best location for embryo placement is at a spot that is about 1-1.5 cm from the topmost part of the uterus (fundus). Embryo transfer is a largely painless procedure. The accurate, quick, and careful placement of an embryo or embryos into the uterus plays a very important role in the success of an IVF procedure. 

Multiple embryo transfer can increase the chances of the success rates of IVF, but this comes with the risk of multiple pregnancies like twins, triplets, and even higher births. This is a problem as multiple pregnancies are generally high-risk pregnancies with chances of complications that can affect both the mother and the fetus. That is why they should be avoided whenever possible. On the other hand, transferring less number of embryos mostly results in singleton pregnancies, but this comes at the cost of a decreased success rate of IVF. So an individualized approach should be undertaken on a patient-to-patient basis.

Benefits and Drawbacks of Fresh vs Frozen Embryo Transfers
Picture courtesy: CNY Fertility

What are the benefits and drawbacks of fresh embryo transfer?

For a couple that wants to conceive immediately, it is understandable why they would want the embryo transfer to be immediate after fertilization. This is the main advantage of fresh embryo transfer; the pregnancy occurs immediately after a successful IVF treatment process. The disadvantages of fresh embryo transfer are related to its immediate nature. Fresh embryo transfer does not allow the time for genetic testing of the embryo. There is also a possibility of interference from the medication that was used to induce the multiple ovulations. These interferences can be able to prevent the ideal hormonal environment that is necessary for implantation. This is particularly so in terms of the receptivity of the uterine lining.

What are the benefits and disadvantages of frozen embryo transfer?

A frozen embryo transfer (FET) is a very common choice for couples that are undergoing IVF. This is because of the many advantages that it offers. These advantages include:

  • Allowing time for the embryo to be genetically tested
  • Allowing the body time to recover from the ovarian stimulation medication
  • Allowing for the embryo to be tested for viability
  • Allowing for the sexing of the embryo when desired
  • Allowing for future use as a means of fertility preservation
  • Freezing can also enable the embryos to be shipped to another location for use

All these factors can result in a higher quality embryo being transferred, which can lead to a better overall environment which can increase implantation success. A disadvantage of frozen embryo transfer is that there is no guarantee that all the embryos will survive being frozen and then thawed. However, the advancement of technology has largely ensured that this risk is eliminated, meaning that most of the embryos survive this process.

Picture courtesy: FertilityIQ

What are the success rates of the different transfer types?

The success rate of the different transfers is a very important factor to consider when deciding on the type of transfer to choose. The good news is that the success rates of the two transfer types are largely the same. Studies that have been carried out observe that there are no significant differences in the pregnancy or the live birth rates between women who had frozen embryo transfer and the ones that did a fresh transfer. 

Other additional studies have shown that maternal age may also not be a relevant factor in the determination of IVF success rates. This applies especially to women that are 40+ and are worried about the success rates of the fresh against the frozen embryo transfer. The process chosen doesn’t make a big difference in the outcome. 

However, it is important to note that the risk of a miscarriage does increase with the age of the woman. The more essential factor to consider when deciding is to look at the success rate statistics of the clinic that is carrying out the IVF treatment and subsequent embryo transfer, including how they compare to the industry-wide rates released by the Society for Artificial Reproductive Technology (SART).

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