Reproductive hormone levels are controlled by signals from the brain. A brain region called the hypothalamus releases gonadotrophin-releasing hormone (GnRH), which stimulates the pituitary gland to produce luteinising hormone (LH) and follicle-stimulating hormone (FSH). LH and FSH stimulate the production of sex hormones, like oestrogen or testosterone. The level of these sex hormones then acts directly on the brain in a feedback system that helps to regulate further hormone production.
