FSH (follicle-stimulating hormone) is released by the pituitary gland in the brain to push the ovaries to develop follicles (the immature sacs that mature and release an egg when we ovulate) and produce oestrogen. As ovarian function naturally declines with age, oestrogen levels drop, and the pituitary gland recognises this and pumps out more FSH to try and get the ovaries to work harder so FSH usually rises in late perimenopause and postmenopause. However, this will not happen consistently in t