FSH hormone, also called follicle-stimulating hormone, is a gonadotropin produced by the pituitary gland. This hormone should be at a concentration of between 3-9 mIU/ml in a woman, as long as she is on the third day of the menstrual cycle.
However, it may happen that a woman has a higher or lower amount of FSH hormone. For example, pregnant women or women suffering from anorexia will have lower than normal FSH values.
On the other hand, women with low ovarian reserve, Turner's syndrome, or a pituitary tumor will have higher FSH values.