Anti-Müllerian Hormone

What is AMH?

Anti-Müllerian hormone (AMH) is produced by the developing egg sacs in a woman’s ovaries called follicles, and in the testes in men.

In the womb, AMH is pivotal in developing a baby’s sex organs. Male babies have high levels of AMH to stop them from developing female sexual organs^[1]. AMH levels are low at birth in women but gradually rise through puberty.

After puberty, women produce more AMH in their ovarian follicles and high levels can indicate a larger supply of eggs. This is known as your ovarian reserve.

Women are born with a definitive quantity of eggs, which declines as they age because of monthly ovulation and the natural breakdown of the ovarian follicles. AMH levels start to fall from the age of 25 to undetectable levels at menopause^[2].

How Does AMH Impact Fertility?

Low AMH levels are not a cause of infertility, but they can give a good indication of the health of your ovarian reserve.

A study published in 2022 involving 665 Indian women undergoing IVF, found that those who had a serum AMH level of ≥1.10 ng/mL (2.46 pmol/L) had:

• A higher number of eggs retrieved
• Good egg quality
• Increased embryo transfer and fertilisation rates^[3]

NICE guidelines state that an AMH level of 5.4 pmol/L or 0.8 ng/mL predicts a low response to ovarian hyperstimulation during IVF treatment while levels above 25.0 pmol/L (3.6 ng/mL) are indicative of a high response^[4]. However, other factors may need to be taken into consideration, such as age and other hormone levels.

It is important to remember that a lower AMH level will not inform you of your chances of getting pregnant, but it can give you an insight into how many eggs you have and if you might reach menopause earlier than average.

Recent research has also shown that high levels of AMH in women could indicate polycystic ovary syndrome (PCOS), a condition which affects 8 to 13% of women of childbearing age^[5]. In these women, rather than reflect ovarian reserve, high AMH could be a biomarker for PCOS severity and indicate a poor reproductive prognosis^[6].

How Can I Measure My AMH Levels?

You can measure your AMH levels with an AMH blood test to get a better understanding of whether your levels are within a normal range for your age.

Unlike other sex hormones, such as follicle-stimulating hormone (FSH), luteinising hormone, oestrogen, and progesterone, AMH doesn’t fluctuate throughout your menstrual cycle, so you can take an AMH blood test at any time.

An AMH blood test can give insight into a woman’s fertility and can identify the number of eggs in the ovaries. It may also help to identify ovarian-related conditions, such as PCOS.

If you are looking to start a family or finding it difficult to conceive, you can check your AMH levels alongside other key fertility hormones with our Female Fertility Blood Test.

What Causes Low AMH Levels in Women?

A lower AMH level can indicate that a woman has fewer eggs in her ovarian reserve than average for her age.

Lower levels are more common as you age, particularly after the age of 40. A low AMH level in younger women can sometimes indicate an increased risk of early menopause.

Research shows that Crohn’s Disease is linked to low AMH and that women of reproductive age with the condition have a lower ovarian reserve^[7].

There are several lifestyle and environmental factors which may contribute to reduced AMH levels. For example, women with higher vitamin D levels maintain their ovarian reserve for longer, meaning this nutrient can have a direct effect on AMH production^[8]. Other factors include:

• Smoking^[9]
• Obesity^[10]
• Stress^[1]
• Alcohol^[12]

What are the symptoms of low AMH in women?

Common symptoms of low AMH are irregular periods that may become shorter or longer and difficulty getting pregnant.
Depending on the cause of low AMH levels, you may experience symptoms associated with an underlying medical condition.

Can low AMH cause miscarriage?

Several recent studies have found a link between low AMH levels and an increased risk of miscarriage. Schumacher et al., (2018) looked at the association between AMH and miscarriage in naturally conceived pregnancies. There were 533 women aged between 30 and 44 with no history of infertility, PCOS or endometriosis included in the study.

The results found that women with significantly low AMH (≤0.4 ng/ml) experienced miscarriages at double the rate of women who had an AMH level of 1 ng/ml or more^[13].

A further study published in 2022, found that early miscarriage rates were lower in women aged under 35 who were having their first egg retrievals for IVF or intracytoplasmic sperm injection (ICSI), with a medium AMH level compared to women with low or high AMH. Young women with a high AMH level were at a significant risk of early miscarriage^[14].

What Causes High AMH Levels in Men and Women?

A high AMH level in women could be a sign of polycystic ovary syndrome or PCOS. PCOS is a common hormonal condition which affects how a woman’s ovaries function^[15]. With PCOS, the ovarian follicles with eggs inside, but the eggs do not fully mature or turn into cysts, resulting in irregular or no ovulation.

Generally, AMH levels are high during foetal development and up until about 6 months of age in boys, slowly declining through childhood before falling to low levels during puberty^[16]. In adult men, high AMH levels could indicate underlying conditions, such as:

• Persistent Müllerian Duct Syndrome
• Androgen Insensitivity Syndrome (AIS)
• Congenital Hypogonadotropic Hypogonadism (HH)
• Testicular dysgenesis
• Varicocele

What are the symptoms of high AMH in women?

If high AMH symptoms in women are caused by PCOS, the symptoms may include:

• Irregular or absent periods
• Difficulty conceiving
• Excessive hair growth usually on the face, chest, back, or buttocks, also known as hirsutism
• Acne
• Hair loss
• Weight gain^[17]

Does high AMH cause/mean poor egg quality?

No, AMH levels tell you how many eggs you have left, also known as your ovarian reserve, it doesn’t reflect the health of your eggs. There is no diagnostic test for egg quality, but naturally, it declines with age.

How To Increase Your AMH Levels

Although you cannot stop the natural decline in AMH as you age, there are several things you can do to support your fertility. They are:

1. Follow a healthy, balanced diet which provides all the vitamins and minerals your body needs to support fertility^[18]. Some research shows that eating dairy foods can reduce the decline of AMH by 47%, milk by 38%, and fermented dairy products by 36%.
2. Research has shown that women who are deficient in vitamin D are more likely to have low AMH^[19]. Our research shows that 61% of the UK population have below optimal levels of vitamin D, with only 19% of women having levels in the ‘healthy’ range (80-10 nmol/L), so if you are looking to conceive it is worth considering vitamin D supplementation, as well as increasing your intake of rich food sources, such as mushrooms, oily fish, and eggs.
3. Stress can have a big impact on your fertility^[20] and it can directly influence AMH levels in women^[21]. It’s important to get enough rest and manage your exposure to stress, especially if you are trying for a baby. Some of the things you can try are exercise, yoga, practising mindfulness, taking up a hobby, and even meeting up with friends and family.
4. Women who currently smoke have been found to have a 44% reduction in AMH compared to non-smokers^[22]. So, if you’re looking for ways to preserve your ovarian reserve, quitting smoking (if you smoke) is a good place to start.

What Biomarkers Should I Test With AMH?

Testing your AMH levels will only give you part of your fertility picture. The results will tell you what your ovarian reserve looks like, but it won’t tell you the quality or quantity of your eggs or if your reproductive organs are healthy.

It is possible to have normal AMH levels and still have trouble conceiving. At Forth, we have a Female Fertility Blood Test which measures seven biomarkers that influence the reproductive system, to give you a more accurate insight into your reproductive health. The biomarkers included in the test are:

• Anti-Mullerian Hormone (AMH)
• Follicle-stimulating hormone (FSH)
• Luteinising Hormone (LH)
• Prolactin
• Thyroid-stimulating hormone (TSH)
• Thyroxine (T4)
• Triiodothyronine (T3)

By measuring this panel of hormones, we can assess for a wide range of risk factors associated with infertility.

Written by Leanne Edermaniger

Based in the UK, Leanne specialises in writing about health, medicine, nutrition, and fitness.

She has over 5 years of experience in writing about health and lifestyle and has a BSc (hons) Biomedical Science and an MSc Science, Communication and Society.