Embryo Freezing vs. Egg Freezing: What’s the Difference?

So here you are, making plans for a potential future pregnancy.

Maybe you’ve decided that you’re not ready for a baby right now, but you’d like to keep the option open for the future. Maybe you (or your partner) are experiencing a medical condition that could delay or seriously impact fertility, and you want to safeguard against any reproductive what-ifs. Maybe you’re focused on other things in your life right now, and kids can come later.

There are a million different reasons to decide to freeze reproductive materials for future assisted reproductive technology (ART) cycles, and all of them are good ones. 

Whatever your reason, at some point you’ll have to choose between egg freezing vs. embryo freezing. People do both, so how do you choose one method over the other? Let’s take a look.

How does egg freezing and embryo freezing work?

ART is the umbrella term for all the infertility treatments that use technology to assist in conception. One of the more common ART methods—and the most common way to implant frozen embryos or embryos made from frozen eggs—is in vitro fertilization, or IVF. 

IVF involves surgically retrieving eggs from a person’s body and fertilizing them with sperm in a laboratory to create embryos. A viable embryo is then transferred into a uterus: yours, your partner’s, a gestational carrier’s, you get the idea. 

>>RELATED: What Should I Try Before IVF?

When the embryo is created using a recently-retrieved egg then immediately transferred to a uterus, the transfer process uses what’s called a “fresh” embryo.

However, eggs and embryos don’t need to be used right away. You can also opt for a banking cycle and cryopreservation after egg retrieval. In a banking cycle, eggs or resulting embryos are frozen, or cryopreserved, and stored for potential later use. (Sperm can also be cryopreserved for later use.)

How does cryopreservation work?

Egg freezing and embryo freezing both start with egg retrieval. Then comes the freezing, either before fertilization (egg freezing) or after fertilization (embryo freezing).

Both eggs and embryos are frozen using either the slow freezing or the vitrification technique. Slow freezing, as the name suggests, is a slower process that takes a couple of hours, whereas vitrification is a flash freeze-like method completed in minutes. Vitrification is now the more commonly-used cryopreservation technique, as this method has been shown to have better egg and embryo survival rates and pregnancy outcomes.

Eggs are frozen right after retrieval. Once embryos have been created in a lab, they can be frozen at different stages of development: at the single cell stage, at the two to eight cell stage, or later on at the blastocyst stage.

Later, if you choose to use your eggs or embryos, they’ll need to be thawed. Not all eggs or embryos survive the thawing process. During the cryopreservation phase, your doctor will freeze as many as possible to try to ensure that you end up with enough viable options for implantation.

If you froze eggs (not embryos), they’ll need to be fertilized with sperm in a lab before they can be implanted in your (or a gestational carrier’s) uterus. If you froze embryos, they can be implanted immediately after thawing. In either scenario, when you implant an embryo created using frozen materials, the process is called a frozen embryo transfer (FET).

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Frozen eggs and embryos transfer vs. fresh embryo transfers

Studies suggest that the rates of successful pregnancies from frozen eggs and frozen embryos are comparable to the rate of successful pregnancies from fresh embryo transfers. And cryopreservation is an increasingly popular choice.

According to the CDC, 38% of all 2020 ART cycles in the United States were banking cycles. CDC data also shows that beginning around 2015, the number of embryo transfers using frozen eggs or frozen embryos surpassed the number of fresh embryo transfers. In other words, it’s now more common for people to use frozen eggs and frozen embryos during their ART cycles.

Comparing embryo freezing vs. egg freezing

The difference between egg freezing versus embryo freezing is when the egg is fertilized and frozen. Egg freezing is when eggs are frozen before being fertilized with sperm, also called oocyte cryopreservation. Embryo freezing is when eggs are fertilized with sperm through in vitro fertilization and the resulting embryos are frozen, also called embryo cryopreservation.

Now for the choice between freezing eggs or freezing embryos. Is one method better than the other? Well, that all depends on you and your circumstances.

Here’s a comparison of some of the factors that may influence your decision, including:

• Cost
• Reproductive autonomy
• Viability after thawing
• Birth rates

Egg freezing vs. embryo freezing: cost

Egg freezing and embryo freezing are pretty similar in terms of price: both procedures are expensive investments. 

>>MORE: Infertility is Expensive. Here Are 7 Ways To Save Money When Trying to Conceive.

Both egg and embryo freezing require egg retrieval and storage, which come with a hefty price tag. Retrieval fees include fertility consultations, medication to help your body produce more eggs, and anesthesia for the procedure. This cost varies depending on the number of retrieval cycles you undergo, and that can change based on age: the older you are, the more cycles may be needed to ensure you have enough viable eggs for successful cryopreservation. 

Retrieval fees plus yearly storage fees add up. Without counting potential future implantation fees, starting costs for the retrieval and cryopreservation process can range from $15,000 to $20,000 per cycle, with yearly storage fees potentially reaching over $500. Some insurance types may cover a portion of these costs but not all do, particularly when cryopreservation is elective.

Freezing price can vary depending on when egg fertilization happens and the number of retrieval cycles necessary to get enough viable materials. These factors are influenced by whether you freeze eggs or embryos.

• Embryo freezing: added fee of lab fertilization; you know how many viable eggs-to-embryos you have after each cycle, reducing costs of undergoing unnecessary egg retrieval cycles
• Egg freezing: no fee of lab fertilization; fee for embryo creation if you choose your frozen eggs. No certainty of viability pre-freeze, potentially leading to more cycles and higher overall cost.

Embryo freezing brings the added fee of lab fertilization before storage. While egg freezing puts this fee off until later, you will eventually have to pay for embryo creation if you choose to use your frozen eggs. Nonetheless, egg freezing can potentially offer a bit more flexibility in the immediate for those who may not be able to cover the costs of egg retrieval and embryo creation.

With embryo freezing, however, you know pre-freeze how many viable eggs-to-embryos you have. This may influence the number of egg retrieval cycles you do. If one cycle gets you enough viable eggs to create enough viable embryos for freezing, you don’t have to undergo more cycles, which can reduce overall cost. With egg freezing, on the other hand, the uncertainty over viability pre-freeze can lead to more cycles, potentially raising overall cost.

Egg freezing vs. embryo freezing: reproductive autonomy

Whether you decide to freeze electively or medical circumstances push you towards your decision, cryopreserving eggs or embryos puts you in the reproductive driver’s seat. That being said, one method does offer more freedom than the other: egg freezing.

Embryos require sperm from a partner or a donor prior to freezing. Eggs, on the other hand, are unfertilized, meaning there’s no need for sperm—or another person—pre-freeze. This grants the freezer an additional layer of reproductive autonomy.

If you don’t currently have a partner, you’re not sure if you want kids with your current partner, or you don’t feel confident that you’ll be with your current partner long-term, you can take control of your fertility on your own. Egg freezing only needs you and your eggs (or a donor’s eggs).

Freezing eggs also bypasses the legal implications of embryos created by two people. If one person—a current or former partner, a sperm donor, whoever—revokes their consent at any point, the embryo they contributed to creating can no longer be used. Frozen eggs, if they come from you, can be used freely, as you wish, whenever you wish, without needing another person’s consent.

Egg freezing vs. embryo freezing: viability after thawing

When you’re ready to use your frozen eggs or embryos, they have to be thawed. Survival rates are somewhat different between the two at this stage of the cryopreservation process.

Evidence suggests that frozen embryos survive the thawing process at slightly higher rates, meaning between a batch of frozen embryos and frozen eggs, you may end up with more viable embryos after thawing. In part, this difference could be because lower quality eggs may not survive thawing. These eggs likely wouldn’t have succeeded in making an embryo pre- or post-freeze, anyway.

A 2023 study reports that eggs survive the freezing and thawing process about 80% of the time. The eggs that survive are then available for use in embryo creation and implantation. Of course, not all thawed (or fresh) eggs will become viable embryos.

According to research on embryo freezing, embryos survive the freezing and thawing process about 90% of the time. 

Despite these differences in exact numbers, it’s important to note that thaw survival rates are high for both eggs and embryos. Regardless of which ones you freeze, the odds are good that you’ll have a lot of viable options for implantation. 

Egg freezing vs. embryo freezing: birth rates

Whether you froze eggs or embryos, an embryo will ultimately be transferred to the uterus after thawing. When you use an embryo created from frozen materials for implantation, whether the entire embryo was frozen or just the egg, you undergo a frozen embryo transfer (FET).

In comparisons of pregnancy and birth rates for FETs versus fresh embryo transfers (transfers with no frozen materials), data frequently examines FETs as a whole without distinguishing whether the embryo itself was frozen or just the egg was frozen.

Still, there are a few figures to suggest that birth rates are essentially the same for frozen eggs and frozen embryos.

For example, according to ART data collected by the CDC in 2020, the birth rate for embryos created from frozen eggs was 47.4%, and the birth rate for frozen embryos was 47.7%. This is a minuscule difference.

Similarly, this 2017 study finds no statistical difference in fertilization rates and birth rates for egg freezing versus embryo freezing.

It’s important to keep in mind that pregnancy and birth rates for embryo transfers—both fresh and frozen—depend on a number of factors, including age at the time of egg retrieval (pre-freeze), age at implantation (post-freeze), and any underlying medical conditions. And just like it’s not possible to guarantee pregnancy with other ART methods, it’s not possible to guarantee future pregnancies through fertility cryopreservation.

Embryo freezing vs. egg freezing: the takeaway

More and more people are choosing to preserve their fertility for later by freezing eggs or freezing embryos. This choice is made for a variety of reasons, both elective and medically-influenced.

Zooming out from the egg versus embryo debate, having a successful pregnancy from a frozen embryo transfer happens about as frequently as having a successful pregnancy from a fresh embryo transfer.

Between egg freezing and embryo freezing, is one method better than the other? Statistically speaking, not really. 

Both eggs and embryos have high rates of survival post-thaw, although frozen embryos tend to fare slightly better than frozen eggs. After implantation, once-frozen eggs and once-frozen embryos have highly similar birth rates. 

What choosing between egg freezing and embryo freezing comes down to is: your life, your choice. When your choice is informed by your unique needs and circumstances, there is no wrong decision.