Fresh vs. Frozen Embryo Transfer: Which Path Is Best?

In most cases, frozen embryo transfer is the best choice for patients rather than a fresh embryo transfer. Following are facts about both options.

During in vitro fertilization (IVF) prospective parents are faced with a decision: Should they transfer their embryo that develops in the lab as soon as it reaches the proper stage, or freeze the embryo(s) for use in a future embryo transfer? The former is called a fresh embryo transfer, the latter is a frozen embryo transfer.

Embryo transfer is a key step in the IVF process, where a fertilized egg develops into an embryo that is placed into the uterus in hopes of achieving pregnancy. It happens toward the end of the IVF timeline, following several essential steps: First, stimulating the ovaries to produce multiple eggs, then retrieving and fertilizing them in the IVF lab.

More parents-to-be are choosing frozen embryo transfer

While both options have their merits, most people select frozen embryo transfers. From 79.8% to 86.1% (figures vary by the mother’s age group) of people doing IVF chose to transfer frozen embryos, according to the United States Department of Health and Human Services. This reflects what we see in our clinic.

This shift away from fresh embryo transfers is due to advancements in cryopreservation techniques that have greatly improved pregnancy outcomes with frozen transfers. In general, the chances of getting pregnant with a fresh or frozen embryo are about the same, with some studies indicating better success with frozen embryo transfer.  An additional advantage of frozen transfer is the option to biopsy and determine if the embryo is euploid (normal chromosomal number) prior to transfer.  

In a few unique cases, we transfer fresh embryos. The right choice for each patient can depend on a variety of individual factors, including health conditions, age and personal preferences. Here’s what to know about both options, and why frozen embryo transfer is more than likely the best choice.

Fresh embryo transfer

A fresh embryo is simply one that has not been frozen (cryopreserved). Embryos are created in the lab by fertilizing an egg with sperm, then they’re transferred to the uterus within days of fertilization in what we call a fresh embryo transfer.

Pros

In a few cases it is not medically advisable for a patient to do a frozen embryo transfer. The primary reason for choosing a fresh transfer is that a couple or individual can proceed with pregnancy immediately after the embryo develops to the proper stage. In this case, patients typically wait no more than five days after egg retrieval for embryo transfer into the uterus.

Cons

Fresh transfers require careful timing. They may not be ideal for everyone, especially if hormone levels rise too high or if ovarian hyperstimulation syndrome (OHSS) is a concern during ovulation induction. For these and other reasons (see below), our fertility doctors generally do not recommend fresh transfer.

Frozen embryo transfer

Frozen embryos go through cryopreservation, where they’re frozen soon after fertilization and stored for future use. When the couple or individual is ready, the embryo is thawed and transferred to the mother’s uterus.

Pros

The major benefit of frozen embryo transfer (FET) is that it offers flexibility for patients who may want or need to delay the transfer due to health, timing or other reasons. Frozen transfers allow additional recovery time for hormones to balance between retrieval and transfer.

(Rare) cons

One potential, though rarely occurring, drawback is that during the embryo thawing process, there is a risk that an embryo may be rendered unviable, which can reduce the number of available embryos for transfer.

Greater benefits with frozen embryo transfer

Deciding between fresh and frozen embryo transfers ultimately depends on a patient’s personal, health and family planning needs. Several variables are involved in an individual’s chances of success with each option.

We discuss these factors with each patient as related to their specific circumstances. RSCNJ predominantly conducts frozen embryo transfers, but some situations call for a fresh transfer.

We know that a major factor for transfer success – whether fresh or frozen – is embryo quality. In particular, those women over age 35 face a higher likelihood of lower-quality embryos, affecting success rates for any kind of embryo transfer. This is where a frozen embryo transfer has a definite edge.

The benefit of preimplantation genetic testing is only for frozen embryos

Only with a frozen embryos can a patient utilize PGT (preimplantation genetic testing) to evaluate the embryo for genetic defects that can cause implantation failure, miscarriage or birth defects in a child. PGT can only be performed on frozen embryos, from which a few cells are taken in a biopsy.

For some patients, such as those of advanced maternal age or who suspect possible genetic issues, PGT is an excellent idea. In these cases of PGT use, frozen embryo transfer is necessary.

Another benefit from PGT is that a patient often has the choice of deciding what sex they want the embryo being transferred to be. This is possible if they have a healthy embryo with male chromosomes and a healthy one with female chromosomes.

Other benefits of frozen embryo transfer

While PGT is one considerable benefit of using frozen embryos, particularly for those of advanced maternal age, there are other advantages.

• Timing flexibility. Frozen embryos allow for transfers on a more accommodating schedule.
• Medical recommendations. In some cases, doctors may recommend frozen transfers if they believe waiting could improve implantation chances.
• Future family planning. For patients who may want to preserve embryos for future pregnancies, freezing offers a long-term solution and peace of mind. With embryo freezing, there usually is only a need for one egg retrieval. Those eggs can be developed into embryos and frozen. Otherwise, each chance for an IVF pregnancy means a new egg retrieval.
• Costs: With IVF failure using frozen embryos, another egg retrieval will not be needed, as the couple will likely have more embryos frozen from the first retrieval. This can reduce costs, particularly if more than two IVF cycles are needed for retrieval and/or successful birth.
• Potential for more healthy embryos. Women can freeze their embryos, or eggs, at a younger age when their egg quality and potential for success is greater. So a woman can wait until she is older and try IVF with frozen embryos from her more youthful days.
• More receptive uterine environment. A fresh transfer must occur usually three-to-five days after egg retrieval. But the mother may still have high estrogen levels from medications to increase egg production. This means her uterus may not be receptive to embryo implantation, risking miscarriage.

We’ll guide you through embryo transfer

Ultimately, patients should make the decision between fresh and frozen embryo transfers with careful consideration of individual circumstances and after speaking to their fertility specialists. We can provide tailored guidance and support based on their unique health profile and goals.

Together, patients and their doctor can navigate this important choice and work toward achieving dreams of parenthood. We believe that in most cases, going with frozen embryo transfer will be the best choice.