Anti-Müllerian hormone (AMH)
The best single blood marker of ovarian reserve — how many eggs a woman has left. Stable across the menstrual cycle, it is used to plan fertility treatment and predict the response to IVF, and it is often high in PCOS.
What it measures
AMH is produced by the small growing follicles in the ovaries, so its level reflects the size of the remaining egg pool (ovarian reserve). Unlike FSH and estradiol, it stays fairly constant through the menstrual cycle, which makes it convenient to measure on any day. It falls gradually with age and becomes very low near menopause. Its main uses are in fertility: estimating remaining reserve, predicting how many eggs an IVF stimulation will yield, and tailoring drug doses. It is frequently elevated in polycystic ovary syndrome, where there are many small follicles. Importantly, AMH predicts egg quantity, not egg quality or natural fertility in any given month — a low value does not mean pregnancy is impossible, nor a high value that it is guaranteed.
What a high value can mean
- Polycystic ovary syndrome (PCOS) — the commonest cause; many small follicles produce a lot of AMH.
- High ovarian reserve — a larger remaining egg pool; can predict a strong (occasionally excessive) IVF response.
- Granulosa cell tumour — rare; a persistently very high AMH without a PCOS explanation.
What a low value can mean
- Diminished ovarian reserve — fewer eggs remaining; expected with age.
- Approaching menopause / primary ovarian insufficiency — very low or undetectable.
- After chemotherapy, radiotherapy or ovarian surgery — reduced reserve.
- A low AMH means fewer eggs, not that natural conception is impossible — it does not measure egg quality or predict any single month's chance.
When to discuss with a doctor
AMH is most useful for planning, not for a yes/no verdict on fertility. A low result in a woman considering pregnancy is a reason to seek fertility advice sooner rather than to give up hope, and may support egg-freezing or earlier treatment. A high AMH with irregular periods and signs of excess androgens supports a PCOS assessment. Because AMH cannot tell you whether you will conceive this cycle, it should always be interpreted with age, FSH, estradiol and the overall picture. Mediora.AI shows AMH against age and its companion hormones; the fertility plan belongs with a gynaecologist or fertility specialist.