Anti-Müllerian hormone (AMH) is produced by small follicles in the ovaries and is one of the most reliable indicators of a woman's ovarian reserve — the number and quality of eggs remaining. Unlike other hormonal markers, AMH remains relatively stable throughout the menstrual cycle, making it a convenient and consistent test that can be taken at any time of the month.

AMH levels naturally decline with age as the pool of available follicles shrinks. A higher AMH indicates a larger ovarian reserve, while a lower AMH suggests fewer eggs remain. It is widely used in fertility assessment, IVF planning, and investigating conditions such as polycystic ovarian syndrome (PCOS) and premature ovarian insufficiency (POI).