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Freezing Eggs vs. Freezing Embryos: The Pros and Cons

frozen embryos vs frozen eggs

Modern science has provided women with more options than ever before when it comes to their bodies and reproductive rights.

Thanks to innovations in egg retrieval and embryo freezing, there are now alternative conception methods for women (and couples) who are looking to delay pregnancy until later in life or who are having difficulty conceiving.

Deciding between freezing your eggs vs. freezing your embryos can be complicated, however. How do you know which one is the best option for you? Both procedures have their advantages and disadvantages. Depending on your specific situation and goals, one might be a better option over the other.

In this article, we will break down the pros and cons of freezing eggs vs. freezing embryos to help you make an informed decision about your reproductive options.

However, it’s important to note that neither egg freezing nor embryo freezing is guaranteed to be successful; it all depends on each person’s unique situation.

Keep reading for our comparison of freezing eggs vs. freezing embryos.

How Are Eggs Frozen?

To begin the egg freezing process, your doctor will typically require you to receive hormone injections for 8-10 days to stimulate your ovaries and produce multiple fertile eggs.

After you have produced enough fertile eggs, extraction occurs. Your doctor will retrieve the eggs through a process called transvaginal ultrasound aspiration. It takes about 15 to 20 minutes to retrieve multiple eggs, only requiring conscious anesthesia.

Next, once the eggs have been harvested, the doctor will freeze them using one of two methods: slow freezing or vitrification.

Slow freezing involves putting the eggs in a sealed container and gradually lowering the temperature, so that the metabolic rates in the eggs decline. A low concentration of cryoprotectants—an agent that protects the cells from forming ice crystals—is also used.

Vitrification involves rapidly freezing the embryos. A much higher concentration of cryoprotectants is used, but since the embryos are frozen so quickly, they don’t have time to form ice crystals.

Advantages of Freezing Eggs

There are many benefits of freezing eggs vs. freezing embryos. Here are just a few of the pros for freezing your eggs.

No Sperm Required

Perhaps one of the biggest advantages of freezing eggs vs. freezing embryos is that egg freezing doesn’t require sperm. The eggs are frozen unfertilized and can be stored for a later date. This is a great option for single women, women in the midst of seeking a sperm donor, or women who aren’t sure if their current partner is the co-parent they are looking for.

Autonomy for Women

Since the eggs can be frozen without needing to be fertilized first, this gives women autonomy and control over their reproductive options. One of the pros of freezing eggs is that women can preserve their fertility independently—whether they have a partner or not.

Since women might choose to delay pregnancy for numerous reasons (e.g. they want to focus on their career first, they are undergoing a medical treatment that might jeopardize their fertility later on, or they haven’t met the right partner or found the right sperm donor yet), freezing your eggs gives you more options in the long run.

Easier to Discard

When deciding between freezing your eggs vs. freezing your embryos, you need to consider what will happen if you decide not to use the eggs/embryos later on and choose to discard them.

Discarding embryos might pose a complicated moral dilemma for single women or couples and may not be allowed in certain faiths. However, freezing unfertilized eggs might make the decision to discard them easier, as they won’t result in a viable pregnancy unless fertilized.
Comparing Egg Freezing and Embryo Freezing A Comprehensive Analysis

Disadvantages of Freezing Eggs

That said, there are also some obvious cons of freezing eggs. Here are a few of them:

Eggs Are More Fragile Than Embryos

There is always the chance of loss during the thawing process both with eggs and embryos. However, since eggs are a bit more fragile than embryos, you may lose more eggs than you anticipated when you decide to thaw them afterwards.

Therefore, if you have a partner now with whom you want to have children in the future, choosing to freeze your embryos instead of eggs might be the better solution.

More Eggs Are Needed for Improving Chances of Pregnancy

When comparing the pros and cons of freezing eggs vs. freezing embryos, it typically takes about 15 or more frozen eggs to eventually result in a successful embryo due to attrition as eggs are thawed, fertilized, and transferred.

As such, you’ll need to have a lot more viable eggs if you plan to freeze your eggs instead of freezing your embryos. This could make the egg retrieval process more complicated.

How Are Embryos Frozen?

The main difference between freezing eggs vs. freezing embryos is that freezing embryos requires sperm/insemination.

The embryo freezing process starts out similar to the egg freezing process. First, you will be required to get hormone injections to stimulate the ovaries and produce several viable eggs.

The eggs will be extracted using the same ultrasound process.

Then, the extracted eggs will be exposed to the sperm, so that fertilization can occur. This process could take anywhere from 16 to 20 hours.

The eggs that are successfully fertilized by the sperm will develop into embryos. The embryos will be kept in an incubator, so that they can develop.

Once they are ready, your doctor will freeze them using either slow freezing or vitrification.

Vitrification actually helps increase the survival rate of the embryos when they are thawed.

Embryos are then stored in liquid nitrogen until they are ready to be used in the future.

Advantages of Freezing Embryos

Some of the advantages of freezing embryos vs. freezing eggs are as follows:

Reduces the Need for Multiple Egg Retrievals

One of the pros of freezing embryos is that it reduces the number of times you may need to retrieve eggs. When you freeze your embryos, you’ll know up front how many eggs were healthy eggs (because they were successfully fertilized) and which ones were not viable before you begin the freezing process.

Higher Success Rate

While the survival rate for freezing eggs vs. freezing embryos is similar, there is actually a slightly higher chance of survival for embryo freezing. Thanks to modern science, about 90% of frozen eggs survive; meanwhile, about 95% of embryos survive.

With frozen embryos, you have more opportunities to transfer fertilized eggs, which means you have a higher chance of pregnancy.

Stronger Structure

Frozen embryos can be preserved longer due to their cellular make-up.

An egg is made up of one cell. During the freezing process, the water is removed from the cell and frozen in liquid nitrogen. The egg is preserved, but it’s also not very sturdy.

An embryo, on the other hand, is made up of a hundred cells. When it’s frozen and the water is removed, it still has a lot of structure, thus making it stronger than an egg.

Disadvantages of Freezing Embryos

There are a few cons of freezing embryos when compared to freezing eggs. Here are a few of them:

Less Autonomy for Women

The process of embryo freezing requires sperm, which means single women don’t have as many options when it comes to reproduction. It also means that they must rely on a partner (or donor) in order to create an embryo.

Also, if a couple freezes their embryos while in a relationship together, but later split up, this can lead to a complicated situation related to what will happen to the embryos.

Choosing to freeze your eggs independently provides women with more options in the future, especially if they want to delay pregnancy for personal reasons, such as to travel or focus on their careers.

Controversial Procedure

In many faiths, embryos are considered a life. Morally, it can make it very difficult to discard of any extra embryos you might have, and it may make you feel as if you have to use all the embryos. This could mean conceiving more children than you intended to have in the first place.

Another con of freezing embryos is that artificial insemination and in-vitro fertilization (IVF) are often considered controversial. Your decision to freeze your embryos to use at a later date may not be accepted by your family and friends.

Which Is the Better Choice? Freezing Eggs or Freezing Embryos?

In the end, the procedure that’s best for you really depends on your current life situation and your goals.

Freezing eggs vs. freezing embryos allows single women to have reproductive autonomy. If you want to delay pregnancy for a personal reason and preserve your fertility when you are in your prime, egg freezing is the better option.

However, if you and your partner plan to have children together in the future and want to delay pregnancy, freezing your embryos might yield better results, as they have a higher success rate and can be frozen longer.

Both freezing eggs and freezing embryos are viable options and make getting pregnant easier for women (and couples) down the road. It’s just a matter of deciding which one is right for you.

ONE Fertility Kitchener Waterloo’s Egg and Embryo Freezing

At ONE Fertility Kitchener Waterloo, our goal is to provide our patients with the best comprehensive fertility care and guidance, so that they can make informed decisions about their fertility journey. We’ll take the time to explain the pros and cons of freezing eggs vs. freezing embryos and come up with a customized treatment option that suits your needs and comfort level.

To learn more about our state-of-the-art fertility clinic, our treatment options, or to discuss the difference between freezing eggs vs. freezing embryos, give us a call or send us an email and we would be happy to answer any questions you might have about our fertility services.


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