What is anti-Müllerian hormone (AMH)?

The hormone plays a role in the development of sex organs while fetuses are growing in the uterus.

AMH levels are highest when you have the largest number of growing follicles in your ovaries. This is typically around the age of 25. After this time, levels naturally decline.

Testing your AMH levels can help determine the number of eggs you have left — your ovarian reserve.

Learn more about the causes and symptoms of high and low AMH and how it affects fertility.

What’s an AMH blood test?

An AMH blood test is a helpful way to understand if your AMH levels fall in the normal range for your age. It’s typically measured alongside thyroid, testosterone, follicle-stimulating hormone (FSH), and oestrogen.

Unlike other hormones, AMH doesn’t fluctuate throughout the month. This means you can do an AMH blood test anytime during your cycle.

It’s important to remember an AMH test can’t directly predict your fertility or the time it will take to conceive. A specialist can give you a comprehensive assessment if you’re trying to get pregnant or want to learn more about your reproductive health.

You can check your egg reserve as part of our AMH blood test.

What’s the normal range for AMH?

The normal range for AMH depends on your age group:

• 18 to 25 — 7.28-104.46 pmol/L
• 26 to 30 — 4.93-95.60 pmol/L
• 31 to 35 — 2.57-71.90 pmol/L
• 36 to 40 — 1.29-40.56 pmol/L
• 41 to 50 — 0.07-21.35 pmol/L

Why is AMH important?

AMH is important because it can give you an indication of how many eggs you have in your ovaries, which can be useful for assessing fertility.

You’re born with a set number of eggs: up to 1-2 million. One of your ovaries releases a mature egg every month when you ovulate. Sometimes you might release multiple eggs.

This means that the number of eggs you have left decreases over time. This number is called your ovarian reserve. And the rate at which you lose eggs is unique to you.

How does AMH affect ovulation?

AMH doesn’t affect ovulation; it reflects the number of eggs left in your ovaries.

The more eggs you have left, the higher the level of AMH in your blood. This is why it’s thought that your AMH levels might be able to indicate:

• your ovarian reserve
• your chances of getting pregnant
• your remaining fertile years

What causes low AMH levels?

AMH levels naturally decline with age, usually starting in your mid-20s. Low AMH levels might indicate lower numbers of remaining follicles and a smaller ovarian reserve.

Certain medical conditions can lead to low AMH levels, including:

• Crohn’s disease — an autoimmune disease where your body attacks parts of your digestive system.
• Rheumatoid arthritis (RA) — a long-term condition that causes painful, swollen, and stiff joints.
• Premature ovarian insufficiency (POI) — you start menopause before age 40.

Other lifestyle factors can lead to low AMH levels, like:

• smoking
• obesity
• poor diet and nutrition, like a vitamin D deficiency
• ovarian surgery

What are the symptoms of low AMH?

The most common symptoms of low AMH levels include irregular periods and difficulty getting pregnant.

Can you increase your AMH levels?

Unfortunately, you can’t meaningfully increase your AMH levels, or increase your ovarian reserve.

While certain things can cause AMH to fluctuate from time to time, it naturally declines with age alongside your ovarian reserve.

While it’s not possible to improve your AMH levels, you can improve your fertility by following healthy lifestyle habits.

These include:

• Following a Mediterranean diet — eating lots of fruits and vegetables, legumes, nuts, beans, cereals, grains, and fish.
• Consuming fewer red and processed meats, sugary drinks, and processed foods.
• Avoiding excessive alcohol intake, smoking, and recreational drugs.
• Losing weight if you’re overweight.
• Staying active — aim for 75 minutes of vigorous-intensity activity or 150 minutes of moderate-intensity activity a week.

For some women, supplements could also be beneficial. These include vitamin D, vitamin B12, omega-3, and folic acid.

How useful supplements are will vary from person to person, and it is generally best to get advice about them from a healthcare professional.

For instance, one meta-analysis found that vitamin D supplementation led to a fall in AMH in women with polycystic ovarian syndrome (PCOS) but a rise in women without this condition.

AMH and fertility

Recent evidence suggests that low AMH levels may give some indication of your chances of getting pregnant.

In a cohort study, women with low AMH levels (less than 1 ng/mL) had a lower chance of getting pregnant compared with women with normal levels (1-5.5 ng/mL).

As a result, it might be a helpful test to include if you’re considering IVF or thinking about family planning. Some fertility specialists measure your AMH levels at the start of your IVF journey — higher AMH levels make it more likely that healthy eggs can be harvested.

It’s really important to remember that in IVF, a woman is under the care of a specialist who can properly interpret their results and provide emotional support.

Miscarriage

A cohort study found that lower AMH levels were associated with a higher risk of miscarriage.

Although this is an interesting finding, it’s based on one small study. More research is needed to confirm these findings and to investigate the possible link between AMH and your risk of miscarriage.

PMOS

High AMH levels are associated with polycystic ovaries and polyendocrine metabolic ovarian syndrome (PMOS) — a common condition affecting how your ovaries work, which can impact fertility.

Egg freezing

If you don’t want to get pregnant until some time in the future, you might have considered freezing your eggs.

Since your AMH levels indicate your ovarian reserve, testing your AMH levels helps you make an informed decision about whether you want to freeze your eggs.

When it comes to harvesting your eggs, most women aim to harvest 12-15 eggs — in a normal cycle, you usually only release one egg. So for this to happen, your ovaries need to be hyper-stimulated with hormones. One study found that your AMH levels might be a good predictor of the number of harvested eggs.

Menopause

AMH levels alone cannot predict menopause with precision, although a systematic review suggests it can give a more accurate picture the further into perimenopause you are.

Menopause is when you permanently stop having periods and can’t get pregnant naturally anymore. Perimenopause is the transitional phase that leads up to it, during which your oestrogen levels begin to fluctuate.

A blood test can’t diagnose menopause. It’s typically based on your age and symptoms.

The only test which can reliably tell you that you’re not releasing eggs anymore is to measure your FSH levels.