WHY does the level of fsh decrease and remain at a low level during days 15-28 of the cycle?

During days 15-28 of the menstrual cycle, the levels of follicle-stimulating hormone (FSH) decrease and remain low due to negative feedback from elevated levels of estrogen and progesterone produced by the corpus luteum. As these hormones rise, they inhibit the secretion of gonadotropin-releasing hormone (GnRH) from the hypothalamus and FSH from the pituitary gland, preventing the stimulation of new follicle development. This hormonal interplay helps regulate the menstrual cycle and prepares the body for potential pregnancy.