Anti-Müllerian Hormone (AMH) testing measures the level of this protein hormone in the blood serum. AMH is produced almost exclusively by the granulosa cells of the preantral and antral follicles in the ovary. Its level reflects the number of active follicles and is therefore considered the most accurate and reliable indicator for assessing ovarian reserve—that is, the quantity and quality of remaining eggs—unaffected by the menstrual cycle or the use of hormonal contraceptives.