Frozen Versus Fresh Embryo Transfer

Introduction:

In recent years, advancements in assisted reproductive technologies have offered a range of options to many couples for achieving their dream of parenthood. One of the best options is frozen embryo transfer or fresh embryo transfer. These are the treatment options during Invitro Fertilization (IVF) or any other infertility treatment. Embryo transfer involves the introduction of an embryo in the mother's uterus undergoing IVF treatment. These embryos are created outside the human body in the laboratory and placed inside the mother's womb. The choice between frozen and fresh embryo transfer is based on a person's decision, age, and previous fertility treatment outcomes. An informed decision can be made by knowing the limits and benefits of both procedures. The article discusses the differences between frozen and fresh embryo transfer, associated risks, techniques, benefits, and complications.

What Is a Frozen Embryo Transfer?

Frozen embryo transfer is a type of assisted reproductive technology. During this procedure, the embryos are frozen outside and then placed inside the womb of the mother at a later date. The overview of the procedure for frozen embryo transfer is as follows:

• Ovarian Stimulation: During this procedure, the first step is ovarian stimulation. The process is similar to fresh embryo transfer. The healthcare provider will inject fertility medications into the woman to stimulate follicles in the ovaries. After the maturation of the follicles, an egg retrieval procedure is performed. During this procedure, the eggs are collected.

• Fertilization: After the collection of eggs, the fertilization process is done in the laboratory. Fertilization of eggs with sperm can be done via insemination and intracytoplasmic sperm injection. During these procedures, every single sperm is directly injected into each egg.

• Embryo Culture: Then, the embryo is cultured for several days. During embryo culture, the laboratory personnel will monitor the quality and development of each embryo. Then the good quality or healthy embryo is selected for cryopreservation.

• Cryopreservation: The cryopreservation process is called vitrification. The selected embryos are frozen or stored for a longer time.

• Endometrial Preparation: The woman's endometrium is prepared by hormone medications, such as estrogen and progesterone. These medications will thicken the uterine lining for embryo implantation.

• Embryo Transfer: After the preparation of the endometrium, the frozen embryos are transferred by using a thin catheter.

• Pregnancy Test: The healthcare provider will advise a blood test after 10 to 14 days of embryo transfer to determine pregnancy.

What Is a Fresh Embryo Transfer?

A fresh embryo transfer is a procedure in which a fresh embryo is transferred shortly after the fertilization of an egg with sperm. The overview of fresh embryo transfer is described below:

• Ovarian Stimulation: The healthcare provider will prescribe some medications to the woman to stimulate follicles in the ovaries. After stimulation, the eggs are collected by using a needle.

• Fertilization: The collected eggs are mixed with the sperm in the laboratory. This is called fertilization. Fertilization can be done by mixing sperm and eggs, or every single sperm is injected into the egg.

• Embryo Culture: Then, the embryo is cultured in the laboratory for several days. The healthcare provider will select a healthy embryo for the procedure.

• Endometrial Preparation: The hormone medications are injected to thicken the uterine lining of the woman's womb.

• Embryo Transfer: After the third to fifth day after fertilization, the fresh embryo is transferred into the woman's uterus. The women may be advised to take progesterone medications to support the luteal phase of the menstrual cycle.

• Pregnancy Test: After 10 to 14 days of embryo transfer, a blood test is performed to determine pregnancy.

What Are the Differences Between Fresh Embryo Transfer and Frozen Embryo Transfer?

The key differences between fresh and frozen embryo transfer are described below:

1. Embryo Transfer Timing: In fresh embryo transfer, the embryo is transferred on the third to fifth day after fertilization, and in the case of frozen embryo transfer, the embryos are frozen for several days.

2. Hormone Medications: These medications are given to prepare the uterine lining for embryo transfer. In fresh embryo transfer, the medications are given in the same cycle as ovarian stimulation, and in frozen embryo transfer, the medications are given in a separate cycle.

3. Success Rates: In the case of fresh embryo transfer, the success rate can be influenced by the timing of embryo transfer and ovarian hyperstimulation. In frozen embryo transfer, the success rate is higher, and the risk of ovarian hyperstimulation is lower.

4. Attempts: In fresh embryo transfer, additional immediate embryos are unavailable at the time of embryo transfer. A new separate cycle needs to be performed to get additional embryos. In the case of frozen embryo transfer, the same batch of frozen embryos are available.

What Are the Benefits of Fresh Embryo Transfer and Frozen Embryo Transfer?

The benefits of fresh embryo transfer and frozen embryo transfer are as follows:

Benefits of Fresh Embryo Transfer:

• In this case, there is an immediate transfer of embryos during the same IVF cycle. People who have less number of high-quality embryos can opt for this procedure.

• The procedure requires less time between egg retrieval and embryo transfer.

• The embryos are transferred shortly after fertilization, so the quality of embryos is high.

Benefits of Frozen Embryo Transfer:

• During this procedure, there is more time to prepare the endometrium. It provides benefits for people with irregular menstrual cycles.

• It reduces the risk of ovarian hyperstimulation.

• The eggs can be stored for future use. It can be used in case of repeated ovarian stimulation.

• It is associated with improved neonatal outcomes and reduces the risk of low birth weight.

• It reduces physical and emotional stress.

What Are the Risks or Complications of Fresh Embryo Transfer and Frozen Embryo Transfer?

The risks and complications of fresh and frozen embryo transfer are as follows:

Risks of Fresh Embryo Transfer:

• The main risk associated with this procedure is ovarian hyperstimulation syndrome. The symptoms associated with this syndrome are abdominal pain, bloating, and fluid accumulation in the chest area.

• Sometimes, the embryo transfer timing does not always align with a woman's natural menstrual cycle. It decreases the chances of successful embryo implantation.

• It increases the risk of multiple babies due to the transfer of multiple embryos.

Risks of Frozen Embryo Transfer:

• During this procedure, the embryo quality may vary, and sometimes, many embryos do not survive.

• There is a need for two separate cycles for embryo transfer.

• The cost of this procedure is high because of cryopreservation and storage.

Conclusion:

In conclusion, fresh and frozen embryo transfer is the aspect of in vitro fertilization. Both procedures have their risks and benefits. Fresh embryos are immediately transferred to the woman's womb, and frozen embryos are stored for several days. The decision of choosing the procedure should be collaborative between the patient and the healthcare provider. The person should openly discuss with the healthcare provider to make an informed decision.