Anti-Müllerian Hormone (AMH)

https://www.ivf.com.au/planning-for-pregnancy/female-fertility/ovarian-reserve-amh-test

https://pmc.ncbi.nlm.nih.gov/articles/PMC7486884

Overview

Anti-Müllerian Hormone (AMH) is a blood test used to estimate functional ovarian reserve, meaning the number of small growing follicles currently active in the ovaries.

It is commonly called an “egg-timer test”, but this phrase can be misleading because AMH does not measure egg quality, does not directly count all remaining eggs, and does not reliably predict natural fertility.

Physiology

Where AMH comes from

AMH is produced by granulosa cells around small developing ovarian follicles, especially:

• primary follicles
• pre-antral follicles
• small antral follicles.

As follicles mature and become dominant, AMH production falls.

(A) AMH Expression During Folliculogenesis

(B)AMH and Ovarian Reserve With Age

AMH is produced by granulosa cells in developing ovarian follicles. AMH expression: – Starts increasing from the secondary follicle stage – Continues rising until the small antral follicle stage Highest AMH production occurs in: – Pre-antral follicles – Small antral follicles In preovulatory follicles: – AMH expression decreases significantly – AMH is only present in the cumulus granulosa cells surrounding the oocyte

Functional ovarian reserve declines with increasing age. This occurs due to gradual depletion of the: – Primordial follicle pool As ovarian reserve declines: – The number of small antral follicles decreases – Serum AMH levels progressively fall AMH levels become: – Very low or undetectable at menopause Therefore, AMH serves as a marker of: – Remaining follicle quantity – Functional ovarian reserve

What AMH does

AMH helps regulate follicle development by:

• limiting excessive recruitment of primordial follicles
• reducing follicle sensitivity to FSH
• helping ensure only a small number of follicles progress toward ovulation.

Functional ovarian reserve

Meaning

Functional ovarian reserve refers to the pool of small active follicles available for recruitment.

These follicles are clinically important because they:

• produce AMH
• can be seen as antral follicles on ultrasound
• may respond to FSH stimulation during IVF.

Important distinction

Concept	Meaning
True ovarian reserve	Total remaining primordial follicle pool
Functional ovarian reserve	Active growing follicle pool
AMH	Marker of functional ovarian reserve

AMH is therefore an indirect marker of ovarian reserve.

AMH and age

AMH generally:

• rises from childhood
• peaks around the mid-20s
• declines progressively after age 25
• declines more rapidly after the mid-30s
• becomes very low or undetectable near menopause.

Approximate age-related pattern

Age	Typical AMH pattern
<25 years	Higher AMH, rising/peak phase
25–34 years	Gradual decline
35–39 years	Decline often becomes more clinically relevant
40–44 years	Lower AMH common
≥45 years	Often very low or undetectable

AMH percentiles

Percentiles compare a woman’s AMH with women of the same age.

Meaning of percentile bands

Percentile band	Meaning
<2.5th percentile	Very low compared with same-age women
2.5th–50th percentile	Lower half of age-matched range
50th–97.5th percentile	Upper half of age-matched range
>97.5th percentile	Very high compared with same-age women

Example interpretation

If a 34-year-old woman has AMH 35.6 pmol/L:

• this is above average for age
• likely within the 50th–97.5th percentile range
• suggests relatively high functional ovarian reserve
• may predict good ovarian response if undergoing IVF.

It does not mean guaranteed fertility or good egg quality.

Approximate AMH interpretation in pmol/L

AMH level	Interpretation
<3 pmol/L	Very low ovarian reserve
3–6.9 pmol/L	Low ovarian reserve
7–14 pmol/L	Mildly reduced / low-normal
15–25 pmol/L	Average range for many reproductive-age women
25–40 pmol/L	High ovarian reserve
>40 pmol/L	Very high; consider PCOS if clinically consistent

These are approximate ranges only. Laboratory assay and age-specific reference intervals are more important than a single universal cut-off.

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Clinical uses of AMH

Fertility assessment

AMH can help with:

• fertility counselling
• assessment of reduced ovarian reserve
• IVF planning
• egg freezing counselling
• identifying likely poor or excessive ovarian response.

IVF and ovarian stimulation

AMH is most useful for predicting ovarian response to stimulation.

Low AMH may predict:

• fewer eggs collected
• poor response to stimulation
• higher risk of cycle cancellation.

High AMH may predict:

• strong ovarian response
• higher oocyte yield
• increased risk of ovarian hyperstimulation syndrome.

ESHRE guidance on ovarian stimulation focuses on individualising IVF stimulation, including prevention of excessive response and OHSS in high responders.

PCOS

AMH may be high in PCOS because women with PCOS often have increased small antral follicle numbers.

High AMH should prompt consideration of PCOS if there are:

• irregular cycles
• clinical hyperandrogenism
• biochemical hyperandrogenism
• polycystic ovarian morphology on ultrasound.

AMH alone should not be used as the only diagnostic criterion.

Premature ovarian insufficiency

AMH may be low in POI, but it is not currently recommended as the diagnostic test for POI.

RACGP states POI is diagnosed by:

• oligo/amenorrhoea for 4–6 months
• FSH >25 IU/L on two occasions at least one month apart
• exclusion of secondary causes of amenorrhoea.

Menopause

AMH may correlate with proximity to menopause, especially in older reproductive-age women, but it is not precise enough to confirm menopause in routine clinical practice.

Do not use AMH alone to:

• confirm menopause
• decide contraception cessation
• predict exact final menstrual period.

Oncology and ovarian toxicity

AMH can be useful before and after gonadotoxic treatment such as:

• chemotherapy
• pelvic radiotherapy
• ovarian surgery.

Low AMH after treatment may reflect reduced follicle pool and increased risk of ovarian insufficiency.

Granulosa cell tumour

AMH can be used as a tumour marker in granulosa cell tumours, usually in specialist care.

Disorders of sex development / delayed puberty

AMH may assist in specialist endocrine assessment of:

• disorders of sex development
• delayed puberty
• gonadal function.

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What AMH does not tell you

AMH does not reliably predict:

• natural conception
• egg quality
• embryo quality
• miscarriage risk
• live birth
• exact menopause timing.

Egg quality vs egg quantity

AMH mainly reflects quantity of small follicles.

Egg quality is mainly determined by age.

So:

• young woman + low AMH: egg quality may still be good
• older woman + normal AMH: egg quality may still be age-affected.

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AMH and natural fertility

AMH should not be marketed or interpreted as a general fertility predictor.

A low AMH does not mean the woman cannot conceive naturally, because spontaneous conception usually depends on ovulating one good-quality egg in a cycle.

A normal or high AMH does not guarantee fertility, because infertility may relate to:

• tubal disease
• endometriosis
• ovulatory dysfunction
• uterine factors
• sperm factors
• age-related egg quality.

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Factors affecting AMH

Hormonal contraception

Hormonal contraception may lower AMH.

This includes:

• combined oral contraceptive pill
• progesterone-only pill
• implants
• possibly hormonal IUDs to a lesser degree.

Effect:

• may cause a false low AMH
• usually reversible after stopping.

Practical approach:

• if AMH is low while using hormonal contraception, interpret cautiously
• consider repeating AMH about 3 months after stopping if the result will affect management.

BMI

Higher BMI is associated with lower AMH.

Possible mechanisms include:

• altered granulosa cell function
• leptin signalling
• metabolic/inflammatory effects.

Clinical interpretation:

• obesity may contribute to relatively lower AMH
• no standard waiting period before testing
• interpret alongside age, AFC, and menstrual history.

Vitamin D

Vitamin D may influence AMH modestly.

AMH may be:

• lower in winter
• higher in summer.

If vitamin D deficiency is significant and AMH is unexpectedly low:

• correct vitamin D
• consider repeat AMH after 2–3 months if clinically important.

Menstrual cycle

AMH is relatively stable across the menstrual cycle compared with FSH and oestradiol.

Specimen can usually be collected:

• any cycle day
• any time of day.

However, some intra-cycle and inter-cycle variation exists, so one result should not be overinterpreted.

Assay variability

Different AMH assays may give different results.

Interpret using:

• same laboratory where possible
• age-specific reference intervals
• assay-specific cut-offs.

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Specimen requirements

• Serum sample.
• Plain tube or SST/gel tube.
• No fasting required.
• No specific cycle timing required.

Cost in Australia

AMH is commonly not Medicare rebated when used for routine ovarian reserve/fertility assessment. Cost varies by provider and laboratory.

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Practical GP interpretation framework

Step 1 — Confirm reason for testing

Common reasons:

• infertility assessment
• fertility planning
• egg freezing discussion
• suspected reduced ovarian reserve
• IVF planning
• prior ovarian surgery
• prior chemotherapy/radiotherapy
• suspected POI.

Step 2 — Check confounders

Ask about:

• current hormonal contraception
• recent cessation of OCP/POP/implant
• pregnancy or postpartum state
• BMI
• vitamin D deficiency
• PCOS features
• ovarian surgery
• chemotherapy/radiotherapy.

Step 3 — Interpret with age

The same AMH result can mean different things at different ages.

Example:

AMH	Age	Interpretation
8 pmol/L	28 years	Low for age
8 pmol/L	41 years	May be expected for age
35 pmol/L	34 years	High-normal / above average
35 pmol/L	42 years	High for age; consider PCOS if symptoms

Step 4 — Correlate with other tests

Consider:

• antral follicle count on pelvic ultrasound
• day 2–5 FSH, LH, oestradiol if indicated
• TSH, prolactin if menstrual irregularity
• androgen profile if PCOS suspected
• semen analysis if trying to conceive
• tubal assessment if infertility context.

Step 5 — Decide action

Low AMH

Consider:

• fertility specialist referral if trying to conceive or planning pregnancy
• discuss not delaying conception if pregnancy desired
• discuss egg freezing if not ready for pregnancy
• check for false low causes
• repeat after stopping hormonal contraception if relevant.

High AMH

Consider:

• PCOS assessment
• cycle history
• androgen symptoms
• pelvic ultrasound
• metabolic risk assessment
• caution regarding OHSS if IVF planned.

Normal AMH

Reassure cautiously:

• ovarian reserve appears age-appropriate
• does not exclude infertility
• continue appropriate fertility work-up if trying to conceive.

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Patient-friendly explanation

AMH is like a blood marker of how many small ovarian follicles are currently active. It helps estimate how strongly the ovaries may respond to fertility treatment.

It does not tell us whether the eggs are genetically normal, and it does not guarantee pregnancy. Age remains the strongest factor for egg quality.

Key take-home points

• AMH measures functional ovarian reserve, not total egg count.
• AMH is best used for IVF planning and ovarian response prediction.
• AMH does not reliably predict natural fertility.
• AMH does not measure egg quality.
• Low AMH does not mean pregnancy is impossible.
• High AMH may suggest PCOS or increased OHSS risk.
• AMH should be interpreted with age, AFC, menstrual history, and clinical context.
• In suspected POI, use menstrual history and repeat elevated FSH, not AMH alone.