Everything you need to know about AMH

If you have been reading up about fertility, or have been undergoing fertility treatment yourself, you may have come across the anti-Mullerian hormone (AMH). The AMH is an important hormone in the body that is related to fertility (1):

1. 1. 1. 1. It reflects the number of eggs present in the ovaries and
         2. Is useful to measure in IVF treatment.

Although this may not make much sense yet,  these three letters ‘AMH’ are worth knowing about – and I hope this article helps answer some questions you may have.

Back to basics
Before describing the AMH, let’s talk about ovaries.

Ovaries are the part of the female reproductive system that is responsible for making and storing eggs. These eggs are responsible for female fertility: they are released from the ovaries, travel to the womb where they meet the male sperm. The egg can then be fertilised to hopefully make an embryo.

However, a woman’s eggs need some help in the body before being ready for release and fertilisation. This is where follicles come in. Follicles are fluid-filled sacs in the ovaries that essentially harbour the eggs. A selected follicle develops and matures throughout the menstrual cycle until the egg it contains is ready for release during ovulation. Compare the egg loosely to a walnut, which grows inside a shell (the follicle) on a tree until it is ready to be released as an edible (fertilisable) nut (egg).

Figure 1: Illustration of ovary and follicle

1. 1. 1. AMH and the ovarian reserve

One of the hormones involved in the maturation of follicles, the shell for the walnut (egg), is the AMH. AMH is present in the ovary until menopause and reflects the number of mature follicles in the ovaries. So, a high amount of AMH in the blood reflects a high number of follicles developing in the ovaries. As mature follicles will eventually release eggs, AMH levels reflect the ovarian reserve: the number of eggs left in a woman’s ovaries. This indicates a woman’s fertility by predicting the number of eggs she has left to release during ovulation, i.e. the amount of time she has left to get pregnant. (2) 

AMH levels can be measured by a blood test at any point during the menstrual cycle. However, they can be affected by certain hormonal contraception, like the oral combined pill for example, so it is best to measure AMH when off hormonal contraception. (3)

Abnormal levels of AMH reflect changes in ovarian reserve; they are not a cause of infertility. Low levels of AMH may reflect various causes of lower ovarian reserve and subfertility, most commonly older age. Other causes of low AMH include previous pelvic operations and chemotherapy. (4) On the other hand, levels of AMH may be high in patients with polycystic ovarian syndrome or rare tumours of the ovary, as both these conditions cause the number of follicles in the ovaries to increase. (2)

1. 1. 2. And what’s the link with IVF?

The main use of AMH today is to help predict how well the ovaries will respond to the medication used in in vitro fertilisation (IVF). AMH levels are measured before IVF treatment to tailor medication doses. Indeed, IVF medication is used to stimulate the follicles to grow and mature, to release an egg needed for pregnancy to develop. The ovaries respond differently based on the number of follicles they contain, this number can be predicted using AMH levels. Extremes of stimulation by the medication – overstimulation, or poor response – can result in a cancelled cycle, meaning that the woman would have to wait for her next cycle to re-attempt IVF treatment. AMH is, therefore, a useful tool to tailor doses of IVF medication to each cycle and woman; for example, a woman with low levels of AMH may require higher doses of IVF medication.

Individualising treatment helps achieve higher success rates of IVF. (2)

Who needs AMH testing?
Testing of AMH levels in the blood is therefore recommended in any woman who wants to screen for a good egg count, women undergoing fertility treatment, as well as in any other woman at risk of a difficult pregnancy.

Remember that having your AMH levels tested does not mean that you have a fertility problem but will help understand how many eggs are present in your ovaries. This will hopefully give you more knowledge and control over your fertility and potential fertility treatments.

References:

1. 1. 1. 1. Wikipedia Contributors. Anti-Müllerian hormone [Internet]. Wikipedia. Wikimedia Foundation; 2019 [cited 2019 Sep 1]. Available from: https://en.wikipedia.org/wiki/Anti-M%C3%BCllerian_hormone
         2. Centre for Reproductive Medicine Anti-Müllerian Hormone (AMH) Testing [Internet]. Available from: https://www.uhcw.nhs.uk/clientfiles/files/IVF/CRM%20AMH%20Patient%20Information%20(GEN-PI-000213V11).pdf
         3. Anti-Müllerian Hormone (AMH) Information leaflet on [Internet]. Available from: https://bwc.nhs.uk/download.cfm?doc=docm93jijm4n3204
         4. Causes of infertility | Background information | Infertility | CKS | NICE [Internet]. Cks.nice.org.uk. 2018 [cited 22 January 2022]. Available from: https://cks.nice.org.uk/topics/infertility/background-information/causes-of-infertility/ 

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