Egg freezing vs embryo freezing: which option is best

Understanding Your Fertility Preservation Options

More people than ever are considering preserving their fertility for the future. Reasons for this vary:

• Delayed Parenthood:
  More people are choosing to have children later in life due to career goals, financial stability, or personal preferences. As fertility naturally declines with age – especially for women – preserving eggs, sperm, or embryos offers more flexibility.
• Medical Treatments:
  Patients undergoing treatments like chemotherapy or radiation (which can impact fertility) often freeze their reproductive cells before treatment to maintain the option of having biological children later.
• Increased awareness and accessibility:
  Advances in reproductive technologies and greater public awareness have made options like egg freezing and embryo freezing more accessible and less stigmatised.
• Genetic Conditions or Family History:
  Some people may preserve fertility early if they have medical conditions or family histories that could lead to infertility later on.
• Improved Success Rates:
  Technology has advanced, so the success rates of using frozen eggs or embryos later on have significantly improved, making preservation more appealing.

Within this article, we will compare Egg Freezing and Embryo Freezing, helping readers to make informed decisions. We will discuss the key differences, costs, success rates and suitability of the two treatment pathways.

What are Egg Freezing and Embryo Freezing?

Egg Freezing

Egg Freezing is a procedure that involves collecting a woman’s eggs from her ovaries and freezing them for use in the future. When you freeze your eggs, they are unfertilised.

Embryo Freezing

Embryo Freezing is a procedure that allows women to store fertilised eggs for later use. These eggs will have been fertilised in a laboratory with either a partner or donor’s sperm. Often, when people undergo in vitro fertilisation (IVF), good quality embryos are left over after embryo transfer. These embryos can be frozen for use in the future.

Other people may choose to freeze their embryos to preserve fertility, so they can use them to try to get pregnant at a later date.

 

Key similarities between Egg Freezing and Embryo Freezing

Both egg and embryo freezing involves daily injections for about 2 weeks to stimulate the ovaries to produce multiple mature eggs. Both treatments involve egg collection whereby the eggs are retrieved through a process called transvaginal ultrasound aspiration. It only takes approximately 20 minutes to retrieve multiple eggs under light sedation.

A key similarity is the way the eggs and embryos are frozen and stored. In both procedures, a process called cryopreservation is used. This involves replacing the water in the cell with a freezing solution called a cryoprotectant, to prevent water in the cells from crystallising. Next, the eggs or embryos are frozen using a ‘fast freezing’ process called vitrification, and stored in liquid nitrogen.

When they’re ready to be used, an embryologist will thaw them, using those that have survived. In embryo freezing, a thawed embryo can be transferred directly to the womb. In egg freezing, the eggs that have survived will be injected with a partner or donor’s sperm for fertilisation, before being transferred to the womb.

Key differences between Egg Freezing and Embryo Freezing

The core difference between Egg Freezing and Embryo Freezing is fertilisation status. Frozen eggs are unfertilised. Frozen embryos are fertilised eggs. There is also a difference in genetic material: an egg contains half the genetic material compared to an embryo. An egg contains 23 chromosomes from the biological mother only. An embryo contains a full set of DNA (46 chromosomes) – 23 from egg and 23 from sperm.

The developmental stages are also different. A frozen egg is a single cell, not capable of developing into a baby on its own. A frozen embryo is a multi-cell organism which has already begun the process of development.

A key difference between egg freezing and embryo freezing is the issue of autonomy. Eggs can be frozen without needing to be fertilised first, which allows women to preserve their fertility independently and decide what eventually happens to their eggs.

With embryo freezing, the embryos belong to two people. This means that if you’ve used a partner or donor’s sperm, they could withdraw consent for the embryos to be used at any time before they are transferred, although it is very rare for a donor to withdraw consent. This means if your circumstances change – a relationship breaks up, for example – you could end up in a situation where you are unable to use the embryos you’ve frozen.

Success Rates: Egg Freezing vs Embryo Freezing?

Since the introduction of vitrification (fast freezing method), the outcome of frozen embryos and frozen eggs has improved significantly. Whilst data is still evolving, it does suggest generally higher success rates per frozen embryo unit compared to eggs. There are however various factors to consider which impact success rates.

Egg Freezing Success Rates

Egg Freezing success rates depend on several key factors:

• A woman’s age at time of egg freezing – egg quality declines with age
• Number of eggs collected – the more eggs frozen, the better the chances. Typically, 10-20 mature eggs are considered ideal to have a good chance of a live birth later.
• Egg quality – whilst quality is closely tied to age, it’s also influenced by genetics, lifestyle and medical history. Poor quality eggs may not survive the freezing and thawing process, or fertilise when inseminated.

Embryo Freezing Success Rates

Embryo Freezing success rates depend on several key factors:

• Age of the egg provider – younger eggs generally create embryos that are more likely to survive freezing and lead to pregnancy.
• Embryo quality – Higher-grade embryos (based on appearance and development) are more likely to survive the thawing process and implant successfully. Embryos that reach the blastocyst stage (day 5-6) tend to have better success rates than earlier-stage embryos (day 3).
• Lab and clinic standards – Embryology lab standards, the experience of embryologists, and freezing/thawing protocols all play a major role.
• Sperm quality – Poor sperm quality can result in lower-quality embryos, affecting their ability to develop, freeze well, and implant later.
• Number of embryos frozen – a greater number of embryos frozen increases the overall chances of achieving a successful pregnancy later. But quality tends to matter more than quantity.

 

Cost Comparison: Egg Freezing vs Embryo Freezing

Embryo freezing is generally more expensive upfront than egg freezing because it involves the entire process of IVF (fertilisation) before freezing, including the cost of sperm, fertilisation and embryo culture. Egg freezing involves only collecting and freezing eggs, a simpler and less expensive process. However, egg freezing may incur deferred costs associated with fertilisation, embryo culture and transfer later.

Here's a more detailed breakdown:

Egg Freezing:

• Upfront Cost:
  The average cost of egg freezing in the UK is around £6,497, but this can vary significantly. This includes the cost of medication, egg retrieval, and freezing.
• Deferred Costs:
  You'll need to factor in the cost of thawing, fertilising, and transferring your eggs later, which can add significantly to the overall cost.
• Storage:
  There are also ongoing storage fees for frozen eggs after your initial storage period ends, typically ranging from £125 to £350 per year.

Embryo Freezing:

• Upfront Cost:
  Embryo freezing is generally more expensive upfront than egg freezing, with costs potentially ranging from £5,000 to £9800. This includes the cost of IVF, including medication, egg retrieval, fertilisation, embryo culture and freezing.
• Lower Deferred Costs:
  Since embryos are already fertilised, there are no further costs associated with fertilization later.
• Storage:
  Similarly, there are storage fees for frozen embryos after your initial storage period ends, typically around £395 per year.

Which is better? Egg Freezing or Embryo Freezing?

Like anything related to family planning, every person is different, so there’s no universal rule around the best approach to preserving fertility – you need to do what’s right for you.

Factors to Consider:

Your personal circumstances and future family planning

Your relationship status will play a part in deciding whether Egg Freezing or Embryo Freezing is the most appropriate fertility preservation treatment. For example, if you’re currently single and don’t know who in the future you’d like to have children with then freezing your eggs is the best option. Equally, for women planning on using a sperm donor in the future then Egg Freezing is the best option.

For women who would like to have children with their current partner at a later date, then freezing embryos might be a better option.

In summary, Egg Freezing provides women with more flexibility in choosing a partner in the future whilst Embryo Freezing commits to the sperm source used.

Whatever your relationship status, discussing your options with a fertility specialist is highly recommended.

Age at freezing

Women are born with approximately 1-2 million eggs at birth.

After age 35, eggs are more likely to have genetic issues (like aneuploidy – the wrong number of chromosomes).

Advancing age negatively affects hormone levels (like FSH and AMH), which are related to the ovaries’ ability to mature and release healthy eggs.

Summary by Age Range:

• Under 30: Optimal egg quality and quantity
• 30-35: Gradual decline in egg quality and quantity
• 35-37: Noticeable decline in egg quality and quantity
• 38-40: Steep drop in egg quality and quantity
• 40-45+: Very few quality eggs remain

Egg quality also affects embryo quality. As mentioned above, as eggs age, they’re more prone to chromosomal errors (like too many or too few chromosomes). When these eggs are fertilised, the resulting embryos often carry the same abnormalities. This can lead to failed implantation, early miscarriage and genetic conditions like Down Syndrome. Sperm quality matters too but egg age tends to be the dominant factor in embryo quality.

So, whether you’re considering Egg Freezing or Embryo Freezing, the younger the age you are when you freeze, the better.

Key similarities between Egg Freezing and Embryo Freezing

Both egg and embryo freezing involves daily injections for about 2 weeks to stimulate the ovaries to produce multiple mature eggs. Both treatments involve egg collection whereby the eggs are retrieved through a process called transvaginal ultrasound aspiration. It only takes approximately 20 minutes to retrieve multiple eggs under light sedation.

A key similarity is the way the eggs and embryos are frozen and stored. In both procedures, a process called cryopreservation is used. This involves replacing the water in the cell with a freezing solution called a cryoprotectant, to prevent water in the cells from crystallising. Next, the eggs or embryos are frozen using a ‘fast freezing’ process called vitrification, and stored in liquid nitrogen.

When they’re ready to be used, an embryologist will thaw them, using those that have survived. In embryo freezing, a thawed embryo can be transferred directly to the womb. In egg freezing, the eggs that have survived will be injected with a partner or donor’s sperm for fertilisation, before being transferred to the womb.

Key differences between Egg Freezing and Embryo Freezing

The core difference between Egg Freezing and Embryo Freezing is fertilisation status. Frozen eggs are unfertilised. Frozen embryos are fertilised eggs. There is also a difference in genetic material: an egg contains half the genetic material compared to an embryo. An egg contains 23 chromosomes from the biological mother only. An embryo contains a full set of DNA (46 chromosomes) – 23 from egg and 23 from sperm.

The developmental stages are also different. A frozen egg is a single cell, not capable of developing into a baby on its own. A frozen embryo is a multi-cell organism which has already begun the process of development.

A key difference between egg freezing and embryo freezing is the issue of autonomy. Eggs can be frozen without needing to be fertilised first, which allows women to preserve their fertility independently and decide what eventually happens to their eggs.

With embryo freezing, the embryos belong to two people. This means that if you’ve used a partner or donor’s sperm, they could withdraw consent for the embryos to be used at any time before they are transferred, although it is very rare for a donor to withdraw consent. This means if your circumstances change – a relationship breaks up, for example – you could end up in a situation where you are unable to use the embryos you’ve frozen.

 

Success Rates: Egg Freezing vs Embryo Freezing?

Since the introduction of vitrification (fast freezing method), the outcome of frozen embryos and frozen eggs has improved significantly. Whilst data is still evolving, it does suggest generally higher success rates per frozen embryo unit compared to eggs. There are however various factors to consider which impact success rates.

Egg Freezing Success Rates

Egg Freezing success rates depend on several key factors:

• A woman’s age at time of egg freezing – Egg quality declines with age
• Number of eggs collected – The more eggs frozen, the better the chances. Typically, 10-20 mature eggs are considered ideal to have a good chance of a live birth later.
• Egg quality – Whilst quality is closely tied to age, it’s also influenced by genetics, lifestyle and medical history. Poor quality eggs may not survive the freezing and thawing process, or fertlise when inseminated.

Embryo Freezing Success Rates

Embryo Freezing success rates depend on several key factors:

• Age of the egg provider – Younger eggs generally create embryos that are more likely to survive freezing and lead to pregnancy.
• Embryo quality – Higher-grade embryos (based on appearance and development) are more likely to survive the thawing process and implant successfully. Embryos that reach the blastocyst stage (day 5-6) tend to have better success rates than earlier-stage embryos (day 3).
• Lab and clinic standards – Embryology lab standards, the experience of embryologists, and freezing/thawing protocols all play a major role.
• Sperm quality – Poor sperm quality can result in lower-quality embryos, affecting their ability to develop, freeze well, and implant later.
• Number of embryos frozen – A greater number of embryos frozen increases the overall chances of achieving a successful pregnancy later. But quality tends to matter more than quantity.

Cost Comparison: Egg Freezing vs Embryo Freezing

Embryo freezing is generally more expensive upfront than egg freezing because it involves the entire process of IVF (fertilisation) before freezing, including the cost of sperm, fertilisation and embryo culture. Egg freezing involves only collecting and freezing eggs, a simpler and less expensive process. However, egg freezing may incur deferred costs associated with fertilisation, embryo culture and transfer later.

Here's a more detailed breakdown:

Egg Freezing:

• Upfront Cost:
  The average cost of egg freezing in the UK is around £6,497, but this can vary significantly. This includes the cost of medication, egg retrieval, and freezing.
• Deferred Costs:
  You'll need to factor in the cost of thawing, fertilising, and transferring your eggs later, which can add significantly to the overall cost.
• Storage:
  There are also ongoing storage fees for frozen eggs after your initial storage period ends, typically ranging from £125 to £350 per year.

Embryo Freezing:

• Upfront Cost:
  Embryo freezing is generally more expensive upfront than egg freezing, with costs potentially ranging from £5,000 to £9800. This includes the cost of IVF, including medication, egg retrieval, fertilisation, embryo culture and freezing.
• Lower Deferred Costs:
  Since embryos are already fertilised, there are no further costs associated with fertilization later.
• Storage:
  Similarly, there are storage fees for frozen embryos after your initial storage period ends, typically around £395 per year.

Which is better? Egg Freezing or Embryo Freezing?

Like anything related to family planning, every person is different, so there’s no universal rule around the best approach to preserving fertility – you need to do what’s right for you.

Factors to Consider:

Your personal circumstances and future family planning

Your relationship status will play a part in deciding whether Egg Freezing or Embryo Freezing is the most appropriate fertility preservation treatment. For example, if you’re currently single and don’t know who in the future you’d like to have children with then freezing your eggs is the best option. Equally, for women planning on using a sperm donor in the future then Egg Freezing is the best option.

For women who would like to have children with their current partner at a later date, then freezing embryos might be a better option.

In summary, Egg Freezing provides women with more flexibility in choosing a partner in the future whilst Embryo Freezing commits to the sperm source used.

Whatever your relationship status, discussing your options with a fertility specialist is highly recommended.

Age at freezing

Women are born with approximately 1-2 million eggs at birth.

After age 35, eggs are more likely to have genetic issues (like aneuploidy – the wrong number of chromosomes).

Advancing age negatively affects hormone levels (like FSH and AMH), which are related to the ovaries’ ability to mature and release healthy eggs.

Summary by Age Range:

• Under 30: Optimal egg quality and quantity
• 30-35: Gradual decline in egg quality and quantity
• 35-37: Noticeable decline in egg quality and quantity
• 38-40: Steep drop in egg quality and quantity
• 40-45+: Very few quality eggs remain

Egg quality also affects embryo quality. As mentioned above, as eggs age, they’re more prone to chromosomal errors (like too many or too few chromosomes). When these eggs are fertilised, the resulting embryos often carry the same abnormalities. This can lead to failed implantation, early miscarriage and genetic conditions like Down Syndrome. Sperm quality matters too but egg age tends to be the dominant factor in embryo quality.

So, whether you’re considering Egg Freezing or Embryo Freezing, the younger the age you are when you freeze, the better.