Infertility is a common issue that affects many couples worldwide, with as many as 1 in 8 couples struggling to conceive. In recent years, assisted reproductive technology has become increasingly popular, offering hope for couples who have been unable to conceive through natural means.
One of the most common forms of assisted reproductive technology is in vitro fertilization (IVF), which involves fertilizing an egg outside the body and transferring the resulting embryo(s) to the uterus. Two methods of embryo transfer are used in IVF: fresh and frozen.
One of the most critical decisions that a couple undergoing IVF must make is whether to opt for fresh or frozen embryo transfer. In this blog post, we will discuss everything you need to know about fresh vs. frozen embryo transfers and help you make an informed decision.
What is an Embryo Transfer?
An embryo transfer is the final step in the in vitro fertilization (IVF) process. It involves the transfer of an embryo or multiple embryos to the uterus with the hope that they will implant and grow into a healthy pregnancy.
The IVF process begins with the stimulation of the ovaries to produce multiple eggs. The eggs are then retrieved and fertilized in a laboratory with sperm from a partner or a donor. The resulting embryos are then cultured for several days before being transferred to the uterus. Embryos can be transferred at various stages of development, depending on whether the transfer is fresh or frozen.
During the embryo transfer procedure, a physician will use a catheter to place the embryos into the uterus. The transfer is typically done under ultrasound guidance to ensure accurate placement. After the transfer, the woman may be advised to rest for a short period and avoid strenuous activities for a few days. It's important to note that not all embryos will result in a successful pregnancy, and multiple transfers may be necessary.
What is a Fresh Embryo Transfer?
A fresh embryo transfer involves the transfer of an embryo to the uterus shortly (usually between 3 and 7 days) after it has been created through fertilization. The resulting embryos are observed for several days to determine their quality.
The highest quality embryo is selected for transfer to the uterus. The timing of the transfer is critical, and it must be synchronized with the woman's menstrual cycle to ensure that the uterine lining is receptive to the embryo.
Some studies claim that fresh embryo transfers are associated with slightly higher success rates than frozen transfers. The success rates for fresh transfers can range from 30% to 60%, depending on various factors such as the age of the woman, the number of embryos transferred, and the quality of the embryos.
That said, there are some disadvantages to fresh embryo transfers such as the need to synchronize the transfer with the menstrual cycle. There is also a risk of ovarian hyperstimulation syndrome (OHSS), a condition that can occur when the ovaries are stimulated to produce too many eggs. OHSS has an incidence of 2-3% in fresh embryo transfers, but it can be life-threatening.
Benefits of a Fresh Embryo Transfer
One of the most significant advantages of a fresh embryo transfer is that it is done in the same cycle as egg retrieval. This means that there is no need to wait for the embryos to be frozen and thawed before transfer.
What is a Frozen Embryo Transfer?
A frozen embryo transfer, on the other hand, involves the transfer of embryos that have been frozen and stored for future use. This method of embryo transfer is becoming increasingly popular, as it offers several advantages over fresh transfers.
The process of freezing embryos involves suspending them in a special solution and cooling them to very low temperatures, which allows them to be stored for an extended period.
This allows for greater flexibility, as the embryos can be stored and thawed when it is convenient for the patient. Additionally, frozen embryo transfers eliminate the need for ovarian stimulation, which can be costly, uncomfortable, and carry some risks.
One study found that the success rates for frozen was between 25% to 50%, depending on various factors such as the age of the woman, the number of embryos transferred, and the quality of the embryos.
Additionally, there is a risk of damage to the embryos during the freezing and thawing process. Some studies comparing the success rate of frozen vs. fresh embryo transfer are conflicting, the difference ultimately seems to be minimal.
Benefits of a Frozen Embryo Transfer
Frozen embryo transfer has some benefits that fresh embryo transfer does not have. Firstly, frozen embryo transfer allows for more flexibility in scheduling the transfer. It is easier to plan for the transfer, and it allows for a more relaxed and stress-free experience.
Secondly, frozen embryo transfer has a lower risk of ovarian hyperstimulation syndrome (OHSS), which is a condition where the ovaries become swollen and painful after egg retrieval. Finally, frozen embryo transfer has a lower risk of multiple pregnancies since fewer embryos are transferred at once.
Success Rates and Risks
Another factor to consider when choosing between fresh and frozen embryo transfer is the success rates. This study found that the birth rate for fresh transfers was 58% while the birth rate for frozen transfers stood between 57% and 63%. In other words, a fairly minimal difference.
It is important to note that success rates may vary depending on the individual's circumstances. For instance, women under the age of 35 may have higher success rates with fresh embryo transfer, while women over the age of 40 may have higher success rates with frozen embryo transfer. It is important to discuss with your doctor which option may be best for you based on your situation.
Another consideration when choosing between fresh and frozen embryo transfer is the cost. Typically, a fresh embryo transfer cycle is less expensive than going through an entire IVF cycle and a separate frozen transfer cycle. This is because fresh transfers are completed within a single cycle and only require one round of medications, while frozen transfers usually require two medicated cycles.
The first cycle involves the retrieval of the eggs and a round of stimulation medications, while the second cycle is required to prime the endometrium and improve receptivity before the embryo transfer. In addition to the medications, the cost of frozen transfers often includes additional fees.
The decision to opt for a fresh or frozen embryo transfer should be made after careful consideration of individual circumstances. Both fresh and frozen embryo transfers have their advantages and disadvantages, and it ultimately comes down to individual circumstances.
