Anti-Müllerian hormone (AMH) is produced by the small developing follicles in the ovaries. A blood test for AMH is used as a marker of ovarian reserve — an estimate of the relative quantity of eggs remaining — and tends to decline with age.
Important caveats: AMH does not measure egg quality, does not reliably predict whether you can conceive naturally, and does not give a precise date for menopause. It is high in PCOS and should always be interpreted with a clinician alongside age and other tests, never in isolation. See AMH and ovarian reserve.