More people than ever are thinking about preserving their fertility for the future. But what’s the difference between freezing eggs and freezing embryos? More importantly, which is the better option for you?
While both procedures have given people more choice around when they have children and how they conceive them, they’re not the same and there’s plenty to think about when trying to choose one over the other.
What’s the difference?
There’s one major difference between freezing eggs and freezing embryos. When you freeze your eggs, they stay unfertilized. We all know that to make a baby, you need an egg and a sperm because each of them provides half of the material needed. On its own, an egg can’t function (and neither can a sperm).
An embryo, on the other hand, is an egg that has already been fertilized by a sperm. Once they combine, the egg and sperm become a single cell. Over the next three to four days, the embryo divides several times, going from one to two to four to eight cells, and so on until it reaches the blastocyst stage and is ready to be frozen. Once an embryo has developed, there’s no going back– that is, there’s no way to turn that embryo back into a separate egg and sperm.
Things to consider
So how does this information help you figure out whether to freeze eggs or embryos? Well, there are two big factors to consider: your circumstances and the research.
If you don’t know who you want to have children with, then freezing your eggs may be the best approach. This option gives you the freedom to hold off on thinking about having a baby until you’ve met someone or are ready to choose a sperm donor.
On the other hand, if you are currently with a partner who you know you’d like to have children with but now isn’t the right time, then freezing embryos might be the way to go. The caveat here is to be 100% certain—stars like Sofia Vergara and more recently, Anna Kendrick, have run into trouble after freezing embryos with partners they didn’t end up with.
Now, let’s look at the research.
Is freezing embryos really better?
The short answer here is not necessarily. The long answer is that each case is unique so whether freezing embryos or eggs is the better option for you will depend on your specific situation and what your labs, imaging, and other health information suggest.
With that in mind, let’s break down the pros and cons of each method.
Pros and cons of freezing eggs vs embryos
Historically, embryos have been “tougher” than eggs and therefore, easier to freeze and thaw. Freezing eggs was much more of a gamble since they’re large cells with a lot of water inside. That water can turn into ice crystals during freezing which, in turn, can damage the chromosomes in the eggs and make them unusable.
But it’s not all gloom and doom for egg freezers! Researchers have continued to study the technology and the statistics have changed as newer and better freezing technologies have emerged. Nowadays, an excellent lab can expect 90% of the eggs that they freeze to survive compared to 95% for embryos.
But, let’s be clear, these numbers don’t mean that your chances of a successful live birth are 5% higher with a frozen embryo, it just means that embryos are a little more likely to make it to the next phase of IVF. The higher quality your frozen eggs (i.e. if you freeze your eggs relatively young and maintain a healthy lifestyle), the more likely they will have thaw rates that are just as good (if not higher) than that of embryos.
A major weakness of egg freezing is that there is no way to test the quality of eggs on their own–they still have to make it through the thawing process, fertilization, and develop into a healthy embryo that can be implanted into the uterus (not all of them make it this far).
This can lead to a situation where someone uses their eggs years after freezing them and those eggs don’t perform as well as they thought they would. By then, this person is older so their egg quality has declined even more. Not having that quality information upfront can make it hard to judge how many eggs need to be frozen to lead to an actual baby.
In contrast, embryos have to get past several important hurdles that give fertility specialists a much better sense of their quality and the chances of a baby later. That’s because turning eggs into embryos requires that they be successfully fertilized and that those embryos survive up to a point where they can be frozen (usually the blastocyst stage, around day 5 of development).
In addition, embryos are graded at each point in their development based on an embryologist’s opinion of whether they are high quality or not (embryologists are experts who study the development of embryos).
Finally, you have the option to run a genetic screening test on embryos, which can help more accurately predict whether they’re likely to become healthy babies. Research has shown that preimplantation genetic screening can result in lower miscarriage rates and higher live birth rates per embryo transfer. There is no such test for frozen eggs.
Chances of a healthy baby down the line
Recent studies comparing the likelihood of actual babies being born, known as the live birth rate (LBR), have shown that it’s now pretty even whether you’re freezing eggs or embryos. Before this, the LBR with frozen eggs was quoted at about 50% the LBR of frozen embryos.
A study published in May 2022 provides even more evidence to support this. The study, done at NYU, is the largest U.S. report of elective fertility preservation outcomes to date and is based on 15 years of real-life frozen egg thaw outcomes for people who had delayed having children and had natural, age-related fertility decline.
On average, study participants were 38 years old at the time they froze their first set of eggs. The study found that regardless of age, those who thawed at least 20 mature eggs had a 58% LBR. This was unexpected given that so many of the participants were past the optimal age to freeze eggs (35 years old or younger). People under 38 years old who thawed 20 or more mature eggs had a 70% LBR per patient. The length of frozen egg storage did not change the success rate.
Additionally, the study found that 39% of people between 27 and 44 years old (most were between 35 and 40 when they froze their eggs) had at least one child from their frozen eggs, which is comparable with age-matched in vitro fertilization (IVF) outcomes. Researchers also found that many of the participants studied had more than one child through egg freezing.
When compared to data collected by the Centers for Disease Control and Prevention (CDC) from the nation’s nearly 500 fertility clinics on people trying to conceive at age 40 using fresh eggs or embryos, only 30% who underwent IVF became pregnant and the LBR was less than 20%.
The final conclusion? For those starting families later, egg freezing and thawing at a later date provides a higher pregnancy success rate than using fresh embryos during assisted reproductive technology.
*One important point the researchers make about their study is that it was limited by the number of patients. More studies need to be done in the future that include people from a variety of geographic locations and center types.
Last, but certainly not least, is the financial side of this. Is embryo freezing more expensive than egg freezing?
Honestly, yes. The upfront cost of egg freezing is definitely less than that of embryo freezing (which requires in vitro fertilization before freezing). While egg freezing costs upward of $10,000 on average, creating and freezing embryos can add a few more thousand dollars to that bill. If you’re freezing embryos using a sperm donor, the sperm can add a further $300 to $4,000, depending on several factors. In both cases, you will also need to pay an annual fee to store your eggs or embryos until you use them. This can cost anywhere from $500-$1000 per year, depending on the clinic you use.
Depending on the type of medical coverage you have, your insurance may cover some of these costs, so make sure you reach out and see what support you can receive from them. Many clinics also offer financial plans and other forms of support so always ask!
TL;DR: Freezing eggs comes with a lower upfront price tag which makes it an easier and more accessible choice than embryo freezing, allowing more people to preserve their future options.
Both the Centers for Disease Control & Prevention (CDC) and experts at Harvard Brigham and Women’s Hospital have developed calculators for assessing a person’s chances of success with artificial reproductive technology (ART). The CDC IVF Success Estimator helps estimate the chances of a live birth with IVF while the BWH Egg Freezing Counseling Tool helps to estimate the chances of at least 1 live birth based on your age and number of frozen eggs.
What do I ask my provider?
Use your health care provider as a support and resource. They should be able to answer any of your questions. Not sure what to ask? Here are a few questions to help you get started:
- How many eggs or embryos do you recommend I freeze, at my current age, to have the highest percentage chance of a live birth later on?
- How many treatment cycles will I need to do to get to this number? It’s totally normal to need more than 1 cycle, but it’s nice to know what to expect ahead of time.
- What is this lab’s rate of successful freezing and thawing of eggs vs embryos (“oocyte cryosurvival rate” is the medical term)? Are they closer to minimal or maximum competency?
- How much would each cycle cost?
- Are there any financial support options, plans, or advice?
- What are the health risks? What about common side effects?
- Is there an upper age limit for using my eggs or embryos in the future?
- How long can I store them and how much will it cost per year?
At the end of the day, there’s no universal rule around the best approach to preserving fertility. Family planning is going to look different for every person so you need to do what’s right for you. When you’re ready, talking to a fertility specialist can help you make up your mind.
In the meantime, Freeze by Co is here to help you every step of the way on that journey. Our Split program allows those who qualify to freeze their eggs for free! In a “Split” cycle, you donate half of the eggs retrieved to a family that’s trying to conceive and freeze the remaining half for yourself. Or, if you don’t want to donate, you can still participate in the Keep program, where you’re able to freeze your eggs and keep them all for yourself, on your timeline. In addition, you’ll have access to our online support community. This valuable resource lets you engage with other people freezing their eggs at the same time!
Whatever you end up choosing for yourself, our team is here to guide you through it and keep your options open.