Egg quality vs quantity in IVF: what your egg count really means

On this page:

What is egg quantity?

What is egg quality?

Egg quality vs egg quantity: why the difference matters in IVF

Why more eggs does not always mean better IVF results

How egg quality affects each stage of IVF

Can egg quality be improved?

When donor eggs may be the best option

Questions to ask if you have had failed IVF cycles

You are more than your egg count

What is egg quality?

Egg quality refers to how likely an egg is:

• to fertilise
• develop into a healthy embryo, and
• lead to a successful pregnancy.

This is harder to measure than egg quantity. Even an egg that looks normal may still have chromosomal abnormalities that stop it from developing properly or increase the risk of miscarriage.

This is why egg quality is often more important than egg count in IVF.

The biggest factor affecting egg quality is age. As a woman gets older, the eggs remaining in her ovaries are more likely to have chromosomal problems. This is one of the main reasons IVF success rates tend to decline with age.

What do we mean by chromosomal abnormalities?

Caption: This image shows a set of human chromosomes. Most people have 23 pairs of chromosomes, with one chromosome in each pair coming from the mother and one from the father. In Down syndrome, there is an extra copy of chromosome 21, so there are three instead of the usual two.

Chromosomal abnormalities are genetic conditions resulting from changes in chromosome number or structure.These abnormalities can already be present in the egg, or they can arise after fertilisation as the embryo begins to divide.

Chromosomes are packages of genetic material that carry DNA. A healthy egg should contain 23 chromosomes. When it is fertilised by a sperm, which also contributes 23 chromosomes, the resulting embryo should have 46 chromosomes in total.

If the egg or embryo has too many, too few, or damaged chromosomes, this can affect development. The embryo may:

• not develop normally
• stop growing after fertilisation
• fail to implant in the uterus
• lead to a miscarriage
• less commonly, result in a baby with a genetic condition

This is why chromosomal abnormalities matter so much in IVF. An egg can look normal in the lab and still carry chromosome errors. And even after fertilisation, errors can still happen as the embryo divides.

The chance of these chromosomal problems increases with age, which is one reason egg quality tends to decline over time.

 

Egg quality vs egg quantity: why the difference matters in IVF

Many patients assume that retrieving more eggs automatically means a better chance of pregnancy. It is understandable to think that way. More eggs can mean more opportunities, but does not always mean better results.

What matters is what happens next.

Dr Vladimiro Silva, Scientific Director of Ferticentro, explains:

“We see patients who produce fifteen eggs in a cycle but end up with one healthy embryo. We also see patients who produce five eggs and get four. The number at retrieval is just the starting point.”

 

What matters is what happens at each stage: fertilisation, development, and ultimately, the quality of the embryos doctors can transfer. That is why IVF is not simply about getting the highest number of eggs possible. It is about giving you the best chance of creating a healthy embryo.

 

Why more eggs does not always mean better IVF results

A higher number of eggs can be useful, but it does not automatically mean a better result. At every stage of IVF, the numbers usually fall. Doctors refer to it as the attrition rate. It means that:

• not every egg collected will be mature
• not every mature egg will fertilise
• not every fertilised egg will keep developing
• not every embryo will reach the blastocyst stage
• not every blastocyst will be suitable for transfer

This is a normal part of IVF. That is why egg numbers only tell part of the story. In the end, embryo quality usually gives a clearer sense of your chances of success.

How egg quality affects each stage of IVF

Understanding what happens during IVF can make it easier to see where quality matters most.

Egg retrieval

After ovarian stimulation, your eggs are collected during a minor procedure, usually under sedation. The number of eggs retrieved depends on your ovarian reserve and how your body responds to the medication.

Fertilisation

Not every egg will fertilise successfully. In IVF with ICSI, where a single sperm is injected directly into each mature egg, fertilisation rates are often good, but some eggs still will not fertilise.

Embryo development

Fertilised eggs are monitored for 5 to 6 days as they develop into embryos. Some will stop growing before they reach the blastocyst stage. This is common and does not mean that other eggs from the same woman will not develop into blastocysts.

Embryo selection

Embryologists assess the embryos based on how they grow, how their cells look, and how they develop over time. This helps identify which embryos are most likely to implant.

Genetic testing

For some patients, preimplantation genetic testing, or PGT, can help identify embryos with chromosomal abnormalities before transfer.

This may be especially relevant if you are of older maternal age, have had recurrent miscarriage, or have already been through failed IVF cycles.

Dr Silva says:

“Genetic testing does not create better embryos, but it can help us identify the ones with the best chance of becoming a healthy pregnancy.”

 

For the right patients, it can make a real difference to their outcomes and to how they experience the process emotionally.

Can egg quality be improved?

This is one of the hardest parts of fertility treatment. Healthy lifestyle choices can support your overall reproductive health, but they cannot meaningfully improve egg quality.

It may still help to:

• avoid smoking
• maintain a healthy weight
• eat a balanced diet
• reduce stress where possible

These steps support your general health, but they do not reverse age related changes in egg quality.

For many women over 38, women with low AMH, or women who have had repeated unsuccessful IVF cycles, egg quality may be the main challenge.

When donor eggs may be the best option

If egg quality is strongly affecting your chance of success, IVF with egg donation may be the most effective treatment option.

Using donor eggs is not a last resort. It is a well established treatment that has helped many people become parents.

Because egg quality usually declines with age, IVF with donor eggs can have higher success rates than IVF with your own eggs if you’re over 40. Donor eggs usually come from younger, healthy women who have been carefully screened.

Dr Silva explains:

“I always encourage patients to see egg donation not as giving something up, but as gaining a genuine opportunity. You carry the pregnancy. You are present at every moment of your child’s development from the very beginning. That bond is real and profound.”

 

At Ferticentro, we match donors and recipients thoughtfully, taking physical characteristics and blood type into account.

We can also offer genetic compatibility testing between the recipient and the selected donor, screening for up to 2,200 gene mutations to help reduce the risk of inherited genetic disorders in children conceived through donation. Read more about our egg and sperm bank here. 

You will also get detailed information about donors, covering physical traits, health history, education and personality factors.

And because it’s an Open-ID donation, although donor identity is protected during the treatment process, Portuguese law allows people born through donor conception to access identifying information when they reach  18.

Questions to ask if you have had failed IVF cycles

If you have already been through one or more IVF cycles without success, it is worth asking your fertility specialist whether egg quality may have been a factor.

Helpful questions include:

• What was the quality of the embryos created?
• Were any embryos genetically tested?
• At what stage did the embryos stop developing?
• Is egg quality likely to be part of the problem?
• Would a different stimulation protocol help?
• Should we discuss donor eggs?

At Ferticentro, we offer consultations for patients who want to review previous treatment and talk through the most appropriate next steps. Contact us at this link. 

You are more than your egg count

Fertility treatment can feel very focused on numbers. AMH levels, follicle counts, fertilisation rates, and embryo grades all matter clinically, but they do not define you or your chances on their own.

Whether you are just starting IVF, preparing for your first cycle, or looking for answers after a difficult experience, Ferticentro’s team is here to offer clear, compassionate guidance based on your individual situation. If you’d like to take the next step, book a consultation with us.