The essential guide to egg quality and egg quantity

On this page:

Ovarian reserve: the foundation of female fertility

How eggs develop during each menstrual cycle

Why egg quantity matters in fertility treatment

How doctors assess egg quantity

What egg quality means

How age affects egg quality

What affects egg quality apart from age?

Why IVF numbers fall at each stage

Can you improve egg quality?

Can you preserve egg quality?

A quick summary: egg quality vs egg quantity

A final word of support

Ovarian reserve: the foundation of female fertility

To understand egg quality and egg quantity, it helps to start with ovarian reserve.

Ovarian reserve means the number of eggs you have left in your ovaries at a given point in time. Your body doesn’t make new eggs, so you are born with all the eggs you will ever have.

What surprises many people is that this starts before birth. While still developing in her mother’s womb, a female foetus already has all the eggs she will ever have. By the time she is born, that number has already fallen significantly. By puberty, it is lower again. From then on, it continues to decline with age.

As Dr Guimarães explains:

 

Ovarian reserve can tell us whether or not there are many eggs still available, but it doesn’t tell us how healthy those eggs are.

How eggs develop during each menstrual cycle

Each egg develops inside a small fluid filled sac called a follicle. During each menstrual cycle, your ovaries recruit a group of these follicles. Usually, one follicle becomes dominant and releases an egg during ovulation. The remaining follicles, along with the immature eggs inside them, stop developing and are reabsorbed by the body.

As the number of remaining eggs falls, the number of follicles available in each cycle often falls too. This is why ovarian reserve is linked to egg quantity.

Why egg quantity matters in fertility treatment

Egg quantity matters because it helps your doctor estimate how your ovaries may respond to stimulation medication during treatment.

In IVF, the aim is to encourage more than one follicle to grow so that multiple eggs can be collected. If you have a higher ovarian reserve, your doctor may be able to retrieve more eggs in one cycle. If your reserve is lower, fewer eggs may develop and be collected.

More eggs can improve the chances of creating an embryo, but quantity is only part of the picture. A high egg number doesn’t automatically mean success, and a lower number doesn’t mean pregnancy is out of reach.

As Dr Guimarães explains,

 

Some people retrieve many eggs but don’t end up with a healthy embryo, while others retrieve only a few eggs and still go on to have a baby.

How doctors assess egg quantity

Doctors usually look at egg quantity using two main tests: AMH and antral follicle count.

AMH and fertility

AMH stands for anti-Müllerian hormone. It is produced by cells in the small developing follicles in your ovaries. Because AMH comes from these follicles, the level in your blood can give an indication of your ovarian reserve.

In general:

• a higher AMH suggests a larger remaining egg supply
• a lower AMH suggests a smaller remaining egg supply

A low AMH result can feel scary, especially if it seems to suggest that time is running out. But a low result doesn’t mean pregnancy is impossible, and it doesn’t automatically mean your egg quality is poor. It mainly tells your doctor that, in an IVF cycle, you may produce fewer eggs.

Dr Guimarães explains that:

 

AMH is helpful when planning treatment, but it is only one piece of the puzzle. On its own, it doesn’t determine your chances of success.

Antral follicle count

Antral follicle count, often called AFC, is another way of estimating ovarian reserve. It is measured using an internal ultrasound scan, which is done through the vagina so the ovaries can be seen more clearly.

This scan is usually done at the start of your menstrual cycle, when the small follicles in the ovaries are easier to see. During the scan, the doctor counts the small fluid filled follicles visible in both ovaries. These are called antral follicles. Each one potentially contains an immature egg, so counting them gives an indication of how many eggs may be available to develop in that cycle.

AFC is useful because it gives a real time picture of how your ovaries are behaving that month. It can help your doctor understand how your ovaries may respond to stimulation medication if you are planning IVF or egg freezing.

Like AMH, AFC helps assess egg quantity, not egg quality. The number can also vary slightly from one cycle to another, so doctors usually look at it alongside your AMH level, age, and wider medical history.

What egg quality means

Egg quality is mainly about whether an egg has the correct number of chromosomes. Chromosomes carry your genetic information.

A healthy egg should contain 23 chromosomes. Healthy sperm should also contain 23 chromosomes. When an egg and sperm join, they create an embryo with 46 chromosomes in total.

If an egg has too many or too few chromosomes, the embryo may not develop as it should. This can mean:

• the embryo doesn’t implant
• it implants but stops developing
• the pregnancy ends in miscarriage
• some of these embryos can still develop into a full term pregnancy, with the possibility of the child being born with a disability.

How age affects egg quality

As eggs age, they are more likely to develop chromosomal errors. This is why egg quality tends to decline over time, and why embryos created from older eggs are more likely to stop developing, lead to miscarriage or generate a chromosomally abnormal fetus.

Age is the biggest factor affecting fertility, but it doesn’t affect egg quantity and egg quality in exactly the same way. In general, both are strongest in your 20s and early 30s, then tend to decline more noticeably from your late 30s onwards.

 

What affects egg quality apart from age?

Age matters most, but it isn’t the only factor that can affect egg quality.

An egg takes around three months to mature before ovulation. During that time, its environment matters. The body can’t create new eggs, but it can influence the conditions in which those eggs develop.

Oxidative stress

Oxidative stress is a type of cell damage that can build up over time. Smoking, poor diet, inflammation, pollution, and ageing can all contribute to it. You can’t prevent it completely, but healthy habits such as not smoking, eating well, and looking after your overall health may help reduce it.

Inflammation and underlying conditions

Some health conditions can affect how eggs develop. These may include:

• endometriosis
• Polycystic ovarian syndrome (PCOS)
• long term inflammation in the body

Smoking

Smoking is one of the clearest lifestyle factors linked to lower fertility

The evidence suggests that light to moderate smoking may have a smaller effect on standard ovarian reserve markers, especially in younger women. However, heavier or long term smoking has been linked to lower ovarian reserve, poorer IVF outcomes and an earlier menopause.

This means smoking may speed up the natural loss of eggs and affect egg quality, which can make it harder to get pregnant.

Environmental exposure

Some research suggests that regular exposure to certain chemicals found in some plastics and everyday products may affect fertility. As Dr Guimarães explains,

 

We still need more research in this area, but it may help to reduce unnecessary exposure where you can.

 

Why IVF numbers fall at each stage

One of the most difficult parts of IVF can be watching the numbers fall at each stage. This is a normal part of the process, even though it can feel disappointing and emotionally draining when you are going through it.

You may start with a good number of follicles on scan, but not every follicle contains a mature egg. Not every mature egg fertilises. Not every fertilised egg keeps developing to day 5 blastocyst stage.

A cycle might look something like this:

• 15 follicles seen on scan
• 12 eggs collected
• 10 mature eggs
• 7 fertilised eggs
• 5 embryos still developing on day 3
• 2 or 3 blastocysts by day 5

Seeing these numbers drop doesn’t mean something has gone wrong. It is an expected part of IVF, even in cycles that are going well.

If there is a bigger drop later in development, especially between fertilisation and blastocyst stage, it can sometimes suggest an issue with egg quality, sperm quality, or both. Embryos often stop developing because they aren’t chromosomally normal.

That can be very hard to hear. But it is also part of how the embryos with the best chance of leading to pregnancy are identified.

Below is a real time-lapse showing a fertilized egg dividing and developing into a blastocyst in the Procriar IVF laboratory.

 

Can you improve egg quality?

You can’t reverse the ageing process or make new eggs, but you may be able to support the health of the eggs that are currently developing.

As Dr Joana Mesquita Guimarães explains,

 

If you are planning IVF or trying to conceive, it can help to think about the three months beforehand as a time to prepare your body.

Supplements often discussed in fertility care

Depending on your situation, your doctor may recommend supplements such as:

• CoQ10
• omega 3
• vitamin D
• melatonin

These may play different roles in supporting overall reproductive health. It’s always best to check with your fertility specialist before starting any supplements, especially if you’re already taking medication or having treatment.

Diet and blood sugar balance

You don’t need to eat perfectly, but a balanced diet can help support your overall health and create a better environment for egg development.

Many doctors recommend a Mediterranean style approach, with:

• healthy fats such as olive oil, nuts, and avocado
• lean protein
• vegetables
• fibre rich foods
• fewer highly processed foods

The goal isn’t perfection. It’s giving your body steady, consistent support.

 

Can you preserve egg quality?

If you’re not ready to have a baby yet but you’re worried about egg quality declining with age, egg freezing may help. It allows you to preserve your eggs at the age you freeze them, which is why doing it earlier can give you a better chance of having healthier eggs stored for the future.

 

A quick summary: egg quality vs egg quantity

Feature	Egg quantity	Egg quality
What it means	How many eggs you have left	How healthy those eggs are
What it shows	Ovarian reserve	Whether the eggs have the right number of chromosomes
How the doctors test it	AMH and antral follicle count	Embryo development, and sometimes PGT A testing
Why it matters in IVF	It influences how many eggs may be collected	It influences whether an embryo can keep developing
Main influence	Age and genetics	Age, cell health, and the environment in which eggs develop
Can it be improved	No, it naturally declines over time	You can’t change age, but you may be able to support the environment around egg development
The aim	Enough eggs to give you more chances	One healthy embryo with the potential to become a baby

 

 

A final word of support

Fertility treatment can be emotionally exhausting, especially when so much seems to come down to numbers. You might feel hopeful, discouraged, anxious, or all three in the same week. That is a very normal part of the process.

Understanding egg quality and egg quantity can help you make more sense of what is happening and what your options may be. But these numbers are only one part of the picture. What matters most is what they mean for you, your plans, and the support you may need next.