As a woman concerned about your fertility and future family planning options, you may be considering methods to preserve your fertility for the future. Two of the most well-known methods are egg freezing (also known as oocyte cryopreservation) and embryo freezing. While the end goal of fertility preservation is the same, egg freezing and embryo freezing processes differ significantly. Understanding how each method works, the pros and cons, success rates and cost implications will help determine which option may be right for your unique situation.
This article provides an in-depth look at embryo freezing, from how embryos are created and frozen to survival rates after thawing to the key factors influencing the chance of a successful pregnancy. We explore how embryo freezing differs from egg freezing, the advantages and disadvantages of each, and what recent research studies reveal about the effectiveness of each method.
After reviewing this guide, you will know to make an informed choice about whether embryo freezing or egg freezing is the optimal fertility preservation method based on your priorities and circumstances. The decision to preserve your fertility is life-changing; we aim to provide the facts you need to move forward confidently.
What Is Embryo Freezing?
Embryo freezing, also known as embryo cryopreservation, is an assisted reproductive technology (ART) where embryos are preserved at extremely low temperatures for later use. The process involves stimulating a woman’s ovaries to produce multiple eggs, which are then fertilized by sperm in a laboratory. The resulting embryos are frozen and stored for future implantation in the woman’s uterus.
The embryo freezing process typically takes around 2 to 6 weeks. First, fertility drugs are administered to stimulate the ovaries to develop multiple follicles. Once mature, the eggs are retrieved in a minor surgical procedure. The eggs are then fertilized in a lab and grown for a few days until they become embryos consisting of 6 to 8 cells. The embryos are then cryopreserved using a technique called vitrification, which involves flash-freezing them in liquid nitrogen. The embryos can remain frozen for many years until the woman is ready to become pregnant.
When pregnancy is desired, the embryos are thawed and transferred into the uterus. Any extra embryos can remain frozen for future use. Embryo freezing is a well-established fertility treatment that has led to the birth of over 5 million babies worldwide. For many, it provides the opportunity to delay pregnancy until the time is right.
How Does Embryo Freezing Work?
Embryo freezing, also known as embryo cryopreservation, is an assisted reproductive technology (ART) used to preserve embryos for future use. Unlike egg freezing which preserves unfertilized eggs, embryo freezing involves fertilizing eggs with sperm to create embryos that are then frozen.
The process begins with ovarian stimulation to produce multiple eggs and IVF to create embryos. The embryos are then frozen at very low temperatures (-196°C) in a process called vitrification until you are ready to have them transferred to the uterus.
Embryo freezing offers some advantages over egg freezing. Since the embryos have already been fertilized, it eliminates the need to find and use donor sperm or a partner’s sperm in the future. It also tends to have higher success rates, with up to 65% of frozen embryo transfers resulting in a live birth. Multiple embryos can be frozen and stored, providing more opportunities for pregnancy from a single cycle.
However, there are also some downsides. There are legal and ethical issues involved with disposing of or donating unused embryos. The freezing and thawing process can be hard on the embryos, potentially reducing the odds of implantation or increasing the risk of birth defects. You also have to go through the full IVF process initially to obtain the embryos, which can be expensive, invasive and time-consuming.
For many, the pros outweigh the cons. If you think you may want children in the future but want to preserve your fertility options today, speaking with a reproductive endocrinologist about embryo freezing may give you the best chance of success when you’re ready.
By planning ahead, you can have the family you want on your own timeline.
Egg Freezing vs Embryo Freezing: What’s the Difference?
Egg Freezing
Egg freezing, or oocyte cryopreservation, involves extracting and freezing a woman’s eggs (oocytes) for potential future use. The eggs are harvested during an egg retrieval procedure, then frozen and stored for later use. When a woman is ready to get pregnant, the eggs are thawed and fertilized with sperm in a laboratory during an in vitro fertilization (IVF) cycle.
- Pros: Egg freezing allows you to preserve your fertility and have biological children later on when you’re ready. It gives women greater reproductive freedom and control over the timing of motherhood. Egg freezing can also reduce the risk of genetic disorders by allowing you to freeze your eggs at a younger age.
- Cons: Egg freezing can be expensive, costing between $5,000 to $20,000 per cycle. It also does not guarantee a future pregnancy. As women age, the quality and quantity of eggs decline, reducing the odds of success. There is also a small risk of damage to the eggs or failure of the eggs to survive the freezing and thawing process.
Embryo Freezing
Embryo freezing involves fertilizing eggs with sperm to create embryos, which are then frozen and stored for later use. The embryos can be transferred to the uterus during an IVF cycle when a woman is ready to get pregnant. Embryo freezing is often done when a couple has extra embryos left over from an IVF cycle.
- Pros: Embryo freezing has a higher success rate than egg freezing alone. Embryos that survive the freezing and thawing process have a greater chance of resulting in a live birth. Embryo freezing is also often less expensive than multiple egg freezing cycles.
- Cons: The main downside is that you need sperm to create the embryos, so embryo freezing requires a male partner or donor. There are also ethical considerations with freezing embryos. Not all of the embryos may be used, bringing up questions about their storage or disposal.
In summary, while egg and embryo freezing are both effective fertility preservation methods, there are significant differences to consider regarding costs, success rates, risks, and ethical issues. The best method for you depends on your own personal circumstances and preferences.
Discuss all your options thoroughly with a reproductive endocrinologist to determine what choice is right for your situation.
Success Rates of Embryo Freezing: What the Research Shows
Success Rates of Embryo Freezing
Research shows that embryo freezing, known as cryopreservation, has been used successfully since the 1980s and currently has a high success rate for achieving pregnancy. According to recent studies, the live birth rate per frozen embryo transfer is between 25 to 35% for women under 35 years old, and between 15 to 25% for women 35 to 39 years old.
- A 2016 study analyzed over 15,000 frozen embryo transfers and found an overall live birth rate of 25.9% per transfer for women of all ages. For women under 35, the live birth rate was 32.8% per transfer.
- A comprehensive review of studies from 2010 to 2019 found that embryo freezing resulted in a cumulative live birth rate of 36.5% for women under 35 after up to three transfers of frozen embryos.
- Pregnancy rates are slightly lower for older women and those with infertility issues like endometriosis or PCOS, but women up to age 44 still have a reasonable chance of success with a frozen embryo transfer.
With today’s advanced freezing techniques like vitrification, embryos can be preserved for longer periods without damage. According to research, frozen embryos stored for up to 5 years have similar success rates to fresh embryos. Some studies report no significant differences in birth rates for embryos stored up to 15 years. However, more research is still needed to confirm long-term success rates past 5-10 years of storage.
In summary, embryo freezing is an established fertility preservation method with high success rates, especially for younger women. Pregnancy success depends on various factors like a woman’s age, infertility diagnosis, and quality of the embryos, but overall, research shows frozen embryo transfers result in live birth rates comparable to or even higher than fresh embryo transfers or egg freezing alone.
Pros and Cons of Embryo Freezing
Increased Chance of Pregnancy
Embryo freezing, also known as cryopreservation, offers some advantages over egg freezing alone. Since the embryos have already been fertilized, their viability and developmental potential can be assessed before freezing. Only high-quality embryos with the best chance of resulting in pregnancy after thawing and transfer are frozen. This helps ensure to reduce the uncertainty of how the eggs will be fertilized after thawing.
Legal and Ethical Considerations
However, embryo freezing also presents some downsides to consider. There are legal and ethical issues regarding the disposition of unused embryos that must be addressed. You will need to determine if the embryos may be used for research purposes or training clinic staff. You will also need to decide if unused embryos may be donated to other couples or if they should be discarded after a certain time period. These decisions can be difficult to make.
Reduced Control
Freezing embryos also provides less control for the woman over how and when the eggs are used since the male partner’s sperm is also involved in creating the embryos. Legal issues regarding the embryos and their use or disposal may arise if the relationship ends. Freezing unfertilized eggs provides full control to the woman over their future use.
In summary, while embryo freezing does have some advantages, there are additional factors to weigh regarding this method of fertility preservation compared to egg freezing alone. Discussing your options with a fertility doctor can help determine what choice is right for your needs and values.
Who Should Consider Embryo Freezing?
Couples Struggling with Infertility
If you and your partner have been trying to conceive for 6-12 months without success, embryo freezing may be an option to consider for fertility preservation. By freezing embryos created from your eggs and your partner’s sperm, you have a chance to try in vitro fertilization (IVF) when you are ready. The embryos can be thawed and transferred to your uterus, with the hope that one or more will implant and develop into a healthy pregnancy.
Women with Medical Conditions
For women diagnosed with cancer or other medical conditions requiring treatments like chemotherapy, radiation, or surgery that could impact fertility, embryo freezing provides the opportunity to have biological children in the future. By extracting eggs, fertilizing them with sperm, and freezing the resulting embryos before treatment begins, you are able to preserve your fertility and options for the future.
Delaying Pregnancy for Career or Personal Reasons
Some women choose to delay pregnancy and childbearing to focus on their careers, education, finances, or other personal reasons. Embryo freezing allows you to create and store embryos during your most fertile years to get pregnant and have a baby when the time is right for you. The younger you are when the eggs are retrieved, the higher the likelihood of success.
In summary, embryo freezing is ideal for women and couples in various circumstances where fertility may be threatened, or pregnancy is not immediately desired. By preserving embryos during peak fertility, the chance of a successful pregnancy and delivery of a healthy baby or baby is greatly improved. With ongoing technological advances, success rates continue to rise, providing hope and options for starting or expanding your family when the time is right.
The Embryo Freezing Process Step-by-Step
Collection and Freezing
The first step in embryo freezing is collecting eggs from the ovaries, either through hormone injections to stimulate egg production or through natural cycle IVF where one egg is collected. Once eggs are retrieved, they are mixed with sperm in a laboratory to create embryos. The embryos are then frozen and stored for future use.
Evaluation
The embryos are evaluated based on appearance and development. The healthiest embryos with the highest chance of implantation after thawing are selected for freezing. Usually, 2 to 8 embryos are frozen for each cycle. Extra embryos can be frozen for future IVF cycles.
The Freezing Process
A cryoprotectant solution is added to protect the embryos during freezing. The embryos are then cooled very slowly in a programmable freezer to -196°C using a technique called vitrification. At this ultra-low temperature, all biological activity stops. The frozen embryos are stored in liquid nitrogen tanks for use when you’re ready to get pregnant.
Thawing and Transfer
When ready to use the frozen embryos, they are carefully thawed and evaluated. Viable embryos are selected for transfer into the uterus using a catheter. Extra embryos can remain frozen for future use. The chance of pregnancy from a frozen embryo transfer is around 50% per cycle for women under 35.
- Embryo freezing has a higher chance of success than egg freezing alone because the embryos have already undergone fertilization and early development.
- Frozen embryos can be stored for many years and still lead to a healthy pregnancy when thawed and transferred.
- Extra embryos left over from an IVF cycle can be frozen instead of discarded, giving patients more chances to get pregnant from just one egg retrieval.
Pros and Cons
Some benefits of embryo freezing include higher success rates, lower cost, and convenience. However, ethical issues like the fate of unused embryos can be complex. You should consider both the medical and ethical factors carefully before deciding if embryo freezing is right for you. Talking to a fertility counsellor can help determine the best path based on your personal values and situation
Conclusion
As you consider your fertility preservation options, egg and embryo freezing offer viable options for preserving your reproductive future. The choice ultimately comes down to your priorities and life plans.
Embryo freezing is the most effective route if you have a partner and want the best odds of success. For those seeking to preserve fertility for future use with an unknown partner, egg freezing provides more control and flexibility.
By understanding the pros and cons of each method, you can choose the fertility preservation option that aligns with your needs and values. While not an easy decision, you can feel confident knowing that you are taking an important step to achieve your goal of having children when the time is right for you.
Anna Haotanto is the Founder of Zora Health and a passionate advocate for women’s empowerment. Anna’s personal experiences with egg-freezing, PCOS, perimenopause and the challenges of fertility have fueled her mission to provide high-quality information, financing, and support to help women and couples navigate their fertility journeys with confidence. She is also recognised for her achievements in finance, entrepreneurship, and women’s empowerment, and has been featured in various media outlets. You can also follow her on Linkedin or Instagram.
