During their fertile years, women go through regular menstrual cycles. These are controlled by hormones and divided into two phases. During the first phase, the so-called proliferation or estrogenic phase, the pituitary gland releases a hormone called follicle-stimulating hormone (FSH). This hormone stimulates the maturation of ovarian follicles. They in turn start to produce oestrogens that lead to the thickening of the inner lining of the uterus (endometrium). A fertile ovum (egg cell) is developing in the ovary. About halfway through the cycle this ovum (egg cell) has matured. The rising levels of oestrogen in the blood then trigger the release of another hormone from the pituitary gland, the luteinizing hormone (LH) that causes ovulation. In the second phase, known as the progestational phase, progesterone is being produced by the corpus luteum (what is left in the follicle after a woman ovulates) which prepares the uterus lining to receive the fertilised ovum. Without fertilisation, the production of progesterone discontinues, the uterus linings decompose and menstruation begins. The production of hormones in ovaries reduces significantly after menopause leading to different menopausal symptoms.

APROM ID# 3079. May 2011.