By Dr Natasha Andreadis, Fertility Specialist at City Fertility Sydney CBD
Fertility specialists will commonly request an Anti-Mullerian Hormone (AMH) blood test as one of the first medical assessments for new patients.
There are two main reasons we use this test – firstly as an initial indicator to evaluate a patient’s egg reserve and secondly to test their response to fertility medication.
Importantly, the results of an AMH test is best interpreted by a fertility specialist, and the gold standard test to determine egg reserve is an antral follicle count (AFC) – a transvaginal ultrasound that counts ovarian antral follicles. An AFC is done ideally in the first half of a woman’s cycle, before ovulation.
What is the Anti-Mullerian Hormone (AMH)?
The anti-Mullerian hormone is produced by the small follicles in the ovary which have not yet begun to develop into mature eggs or ova. These early developing follicles are called antral and pre-antral follicles.
The AMH controls the development of the follicles that the eggs develop from. Its role in the ovary is to limit the progression of all but a very few of the eggs to the final stage, preparatory to ovulation. AMH is produced by the cells surrounding each of the eggs with levels correlating with the total number of viable eggs (or the ovarian reserve).
However, AMH levels do not measure the quality of the eggs, which is also very relevant for success.
The amount of AMH in the blood usually remains constant until the age of 25 then begins to decline. A steady decline of AMH occurs from the age of 35 until it becomes unmeasurable at menopause.
AMH testing for fertility status
Your doctor may recommend an AMH test if: you are having ongoing trouble falling pregnant; you are wanting to delay childbirth and are under 35 years old; or you are concerned about medical conditions that may have an impact on your fertility like a family history of premature menopause, multiple operations on the ovaries, chemotherapy, endometriosis, or polycystic ovarian syndrome.
Importantly, for younger patients, fertility can still be higher at lower levels of AMH (compared with older patients with similar levels) as egg quality is normally better when younger.
AMH testing for response to fertility treatment
If you are undergoing fertility treatment your specialist may choose to do an AMH test to predict ovarian response to fertility medication and helps in deciding the dose of medication (FSH) to be used.
What the results can indicate?
A low ovarian reserve result may indicate:
- it may be better to consider your options for starting a family sooner rather than later
- depending on situation and age, that further assisted fertility methods should be considered
- if already undergoing treatment, may call for a larger dose of fertility medication.
A high ovarian reserve level may indicate:
- polycystic ovaries: people with PCOS have high levels of AMH (often above the 97.5 percentile for age), which should drop with appropriate treatment
About the test?
The AMH blood test can be performed at any time throughout the menstrual cycle.
It may be performed in conjunction with an antral follicle count (simple ultrasound) as a predictor of ovarian reserve.
An AMH test is a good snapshot of current ovarian reserve. However, it is recommended to treat ‘normal results’ with caution and ongoing monitoring is wise as AMH levels decline at predictable rates. Patients must also remember that egg reserve levels are only one of the many factors that can impact fertility.
It is therefore essential for this test to be ordered by gynaecologists and fertility specialists who are trained to interpret the results and explain them in detail to the patient involved. It is important to note that many patients who have low AMH levels still fall pregnant.
