Anti-Müllerian hormone measures the size of your egg supply. It does not measure egg quality. It does not tell you when your fertility ends. And a low number does not mean you cannot get pregnant - it means you may have fewer tries, not no tries.
AMH has become the most talked-about fertility biomarker, partly because it's easy to draw (no cycle-day timing required) and partly because it produces a number that feels definitive. Women receive their AMH result in a vacuum and read it as a deadline. It is not a deadline. It is a gauge.
What AMH actually measures
AMH is secreted by the granulosa cells of small antral follicles - the pool of developing eggs waiting in the ovary at any given time. A higher AMH indicates a larger pool; a lower AMH indicates a smaller one. Because this pool declines with age, AMH does correlate with reproductive age. But the relationship is probabilistic, not deterministic. Women with low AMH conceive naturally every day.
Crucially, AMH says nothing about the chromosomal quality of those eggs. Egg quality is largely a function of chronological age - specifically, the age at which meiosis completes. A 28-year-old with low AMH has the egg quality of a 28-year-old. A 42-year-old with high AMH has the egg quality of a 42-year-old. The age of the woman matters far more than the AMH level when it comes to pregnancy outcomes.
The PCOS misread
Women with PCOS often have very high AMH - sometimes three to four times above the average for their age. This reflects the large antral follicle count that characterises the condition, not exceptional fertility. High AMH in PCOS means many follicles that struggle to ovulate. The fertility barriers in PCOS are ovulatory and metabolic, not a function of reserve.
What AMH is actually useful for
- Baseline for egg freezing decisions - lower reserve may suggest earlier rather than later.
- Predicting ovarian response to stimulation protocols in IVF - higher AMH generally means more eggs retrieved.
- Monitoring decline over time - serial AMH values show trajectory, which is more informative than a single number.
- Flagging premature ovarian insufficiency - AMH below 0.1 ng/mL in a woman under 40 warrants further evaluation.
How to use your result
If your AMH is lower than expected for your age, the useful question is not 'am I running out of time?' but 'does this change any decision I was about to make?' For some women, the answer is yes - they accelerate a conversation about partnership, timing, or egg freezing. For others, the number is a data point that changes nothing practical. Both are valid responses.
What AMH cannot do is tell you whether you will get pregnant, how quickly, or by what means. For that, you need a full fertility workup - day-3 and day-21 labs, a semen analysis, and a clinical evaluation - not a single hormone value.