AMH
Anti-Müllerian Hormone
What it is
Anti-Müllerian hormone (AMH) is a glycoprotein hormone produced by the granulosa cells of small antral and preantral follicles in the ovary. Its physiological role in adult females is to inhibit the recruitment of primordial follicles into the growing pool — AMH produced by developing follicles suppresses further follicle activation, preserving the remaining primordial follicle reserve. Because AMH is secreted directly by antral follicles, its circulating level reflects the size of the remaining follicle pool — the ovarian reserve — in direct proportion. As the primordial follicle pool is fixed at birth and depleted throughout reproductive life, AMH declines progressively with age, reaching undetectable levels at menopause. AMH is largely independent of the menstrual cycle — unlike FSH and oestradiol, which fluctuate substantially across the cycle, AMH can be measured at any time of the month and remains relatively stable, making it the most reliable single blood marker of ovarian reserve. In males, AMH is produced by Sertoli cells during fetal development and childhood (where it is responsible for regression of the Müllerian ducts), falling to very low levels after puberty.
Why we measure it
AMH is the earliest quantitative signal of ovarian ageing. Its clinical significance spans three domains. First, reproductive planning: AMH below the age-expected range indicates diminished ovarian reserve — a reduced capacity to respond to ovarian stimulation for assisted reproduction and a reduced window before natural fertility is substantially compromised. Women with low AMH have fewer eggs retrieved during IVF cycles and lower live birth rates per cycle, independent of age. Second, timing of menopause: prospective studies including the SWAN cohort have found that AMH levels predict the timing of the menopausal transition with reasonable accuracy — very low AMH in a woman in her early 40s predicts earlier menopause, allowing proactive planning for the hormonal transition and its cardiovascular and skeletal consequences. Third, hormonal planning: the onset of perimenopause — the period of erratic ovarian function preceding menopause — is closely associated with a steep AMH decline. Annual AMH tracking detects this transition, providing a quantitative signal that a woman is entering the perimenopausal window and may benefit from hormonal monitoring at the Pulse+ biannual draw. AMH is also elevated in polycystic ovary syndrome (PCOS), where the excess of small antral follicles produces elevated AMH — often 2–4 times the age-expected range — reflecting follicular arrest rather than abundant reserve.
Why every 12 months
Annual AMH testing provides sufficient resolution to track the pace of ovarian ageing. The rate of AMH decline is approximately 4–6% per year in reproductive-age women, accelerating in the decade before menopause. Annual measurement detects a steeper-than-expected decline and allows proactive discussion about reproductive timelines, fertility preservation, and hormonal monitoring.
What movement means
AMH reference ranges are age-dependent and assay-specific. Values must be interpreted against age-matched normative data. AMH is reported in pmol/L or ng/mL; the conversion is 1 ng/mL = 7.14 pmol/L. Approximate median values by age: 25–30 years: ~20 pmol/L; 35–40 years: ~12 pmol/L; 40–45 years: ~5 pmol/L.
Elevated (Possible PCOS)
> 40 pmol/L (> 5.6 ng/mL) in reproductive-age females
Substantially above the age-expected range. Commonly associated with polycystic ovary syndrome, where excess small antral follicles produce elevated AMH. Does not indicate abundant reserve in the way that a normal AMH does — in PCOS, the follicles are arrested rather than maturing normally. Warrants clinical assessment for PCOS.
Dewailly D et al., Human Reproduction Update, 2014 — doi:10.1093/humupd/dmt062
Normal for Age
Within age-matched reference interval (laboratory and assay-specific)
Appropriate ovarian reserve for the individual's age. Annual tracking to monitor the pace of decline relative to expected age-related trajectory.
Nelson SM, Human Reproduction, 2013 — age-specific normative reference ranges
Low for Age
Below age-matched 10th percentile (laboratory and assay-specific)
Diminished ovarian reserve for the individual's age. Associated with reduced response to ovarian stimulation for IVF, reduced natural fertility, and earlier anticipated menopause. Warrants reproductive counselling, specialist review, and discussion of fertility preservation if reproductive planning is relevant.
Broer SL et al., Fertility and Sterility, 2011 — doi:10.1016/j.fertnstert.2010.08.007
Very Low / Undetectable
< 1.5 pmol/L (< 0.2 ng/mL)
Severely diminished ovarian reserve, approaching menopausal levels. In women under 40, this may indicate premature ovarian insufficiency (POI) and warrants investigation including FSH, oestradiol, and karyotyping if indicated. Natural conception is unlikely; fertility specialist referral is appropriate.
European Society of Human Reproduction and Embryology (ESHRE) Guideline on POI, 2016
In the protocol
References
- 1.
Broer SL, Mol BWJ, Hendriks D, Broekmans FJM. “The Role of Antimullerian Hormone in Prediction of Outcome after IVF: Comparison with the Antral Follicle Count.” Fertility and Sterility. 2009.
- 2.
Sowers MR, Eyvazzadeh AD, McConnell D, et al.. “Anti-Mullerian Hormone and Inhibin B in the Definition of Ovarian Aging and the Menopause Transition.” Journal of Clinical Endocrinology & Metabolism. 2008.
- 3.
Dewailly D, Andersen CY, Balen A, et al.. “The Physiology and Clinical Utility of Anti-Mullerian Hormone in Women.” Human Reproduction Update. 2014.
- 4.
European Society of Human Reproduction and Embryology (ESHRE) Guideline Group on POI. “ESHRE Guideline: Management of Women with Premature Ovarian Insufficiency.” Human Reproduction. 2016.