Fresh Vs Frozen Embryo Transfer

During the initial stages of in vitro fertilization (IVF), fresh embryo transfer was the only option available. This is because the technology of cryopreservation—the freezing of embryos for later use—was in its early stages. In the 40 years after the first embryo was successfully transferred, cryopreservation techniques, culture media (the environment in which the embryo grows), and advanced reproductive technology have advanced dramatically, making fresh and frozen embryo transfers (FETs) readily available. FETs are presently the favored transfer type, however both are used often.

The Difference Between Fresh and Frozen Embryo Transfer

Frozen and fresh embryo transfers both start with ovulation induction and monitoring. When the uterus is ready, the woman will have an egg retrieval, in which the reproductive endocrinologist will fertilize her eggs with her partner’s or sperm donor’s sperm.

Once the eggs and sperm have been collected and fertilized, a fresh embryo transfer will take place three to five days later, placing the fertilized embryo back into her uterus.

In contrast, a frozen embryo transfer (FET) can take place years after a woman’s egg retrieval and sperm fertilization. During a FET, your fertility specialist will implant a thawed embryo into the woman’s uterus in the hopes of a successful conception.

Fresh embryo transfer process step by step

• A fresh embryo transfer usually takes place 5 days after a patient’s eggs are extracted.
• The eggs are fertilized with sperm in the laboratory, and the resulting embryo is carefully observed.
• The main advantage of a fresh embryo transfer is a shorter time to conception, as there is only a 5-day wait between egg retrieval and embryo transfer back into the uterus.

NOTE:  There are several contraindications to a fresh IVF transfer. If a patient’s progesterone level is high, a fresh transfer should be avoided since it will have a negative impact on embryo implantation. Similarly, if a patient is at risk of hyperstimulation due to the medications used to enhance egg maturation, a fresh transfer may be risky.

Frozen embryo transfer process step by step

• During the FET cycle, your embryos are frozen and transferred to your uterus.
• This is done when your menstrual cycle is most favorable for pregnancy.
• An IVF frozen embryo transfer typically takes place 6-8 weeks after the embryo is frozen.
• Once the patient is prepared for the transfer, she is given medications that imitate a natural menstrual cycle, and the FET date is timed to coincide with the cycle for optimal implantation.

Benefits of Frozen Embryo Transfer

• If the patient chooses to have her embryos examined for genetic problems, a FET is necessary. Preimplantation genetic testing (PGT) occurs immediately after egg retrieval. The embryo is biopsied by taking a small sample of the embryo’s DNA and evaluating it for chromosomal and genetic abnormalities. Once PGT is complete, the embryologist can select only chromosomally healthy embryos for transfer. Transferring just the normal embryos improves pregnancy success significantly.
• Freezing an embryo can also be useful for additional pregnancies years later because embryos can be preserved indefinitely. 
• With FET, you won’t need to go through another egg retrieval operation because you already have a batch of embryos ready to use. The only medications you’ll need to consider are those that help thicken your uterine lining in preparation for your embryo transfer, lowering the stress on your body.
• If a patient desires to maintain fertility due to age, cancer treatment, or other reasons, frozen embryos can be generated for later use.

When does frozen transfer work best?

In some cases, frozen embryo transfer may be the best alternative, including the following:

High progesterone levels: When progesterone levels are high during egg extraction, the window of uterine receptivity is more likely to shift forward. In these circumstances, it is often preferable to store the embryos and then transfer them when the uterus is receptive again.

Polycystic ovary syndrome (PCOS): Research has shown that women with PCOS benefit more from frozen versus fresh transfer. Frozen transfer lowers the risk of ovarian hyperstimulation syndrome (a consequence of egg retrieval) and increases the likelihood of maintained pregnancy.

Embryos requiring genetic testing: Genetic testing of embryos is time-consuming. As a result, by the time a verified embryo is prepared for transfer, the window of uterine receptivity will most likely have closed. In this situation, frozen embryo transfer is usually preferable.

Frozen and Fresh embryo transfer success rate

When it comes to success rates, both FET and fresh need to investigate a variety of parameters. When determining whether to freeze your embryos or pursue a fresh transfer, you should examine your age or the age of the donors during embryo freezing, the quality of the sperm used for fertilization, and your overall health during both transfers.

• Greater quality embryos are linked to a greater live birth rate.
• However, poor-quality embryos are linked to a low birth rate.
• If you opt to freeze your embryos or participate in a fresh embryo transfer before the age of 35, your chances of getting higher-quality embryos improve.
• However, if you opt to freeze your embryos or participate in a fresh transfer after the age of 35, the odds of getting low-quality embryos increase.

So, regardless of whether you transfer fresh or frozen embryos, your age will play an important role in producing high-quality embryos. Now that we’ve identified the success percentages, let’s look at the advantages of FET versus new transfers.

FAQ’s