What AMH actually measures
Anti-Mullerian hormone is secreted by granulosa cells of small growing follicles, mainly the preantral and small antral pool. Because the size of that pool tracks the larger resting primordial reserve, a blood AMH level serves as an indirect marker of how many eggs remain. It does not count eggs directly and it says little about egg quality, which is driven more by chronological age.
AMH is relatively stable across the menstrual cycle, which is why it can be drawn on most days, unlike day-3 FSH. Levels generally decline with age and fall more steeply after the mid-thirties, mirroring the accelerating loss of the follicle pool.
How clinicians read a reserve result
A low AMH suggests a smaller remaining follicle pool and often predicts a weaker response to ovarian stimulation in IVF, which informs dosing decisions. A high AMH is common in polycystic ovary syndrome because of the large number of small follicles. AMH alone does not diagnose infertility, and many people with low AMH conceive naturally.
Values vary by assay and laboratory, so a single number is best interpreted alongside antral follicle count, age, and the clinical picture. This is general educational information, not medical advice; reproductive testing and family-planning decisions should be discussed with a qualified clinician.