In order to understand what happens to a woman’s body as she ages, it is necessary to review the normal menstrual cycle. The purpose of the menstrual cycle is to prepare a woman for pregnancy through the following hormonal steps:
The pituitary gland near the brain releases a chemical called follicle stimulating hormone (FSH). FSH causes an egg to mature in the ovary and signals the production of estrogen.
• Estrogen stimulates the lining the uterus to thicken, creating an acceptable environment for a potential fertilised egg.
• The pituitary gland releases another chemical called luteinizing hormone (LH). LH causes the egg to be released from the ovary and travel to the uterus (in anticipation of being fertilized).
• Meanwhile, the part of the ovary from which the egg was released (the corpus luteum) begins to produce progesterone.
• Progesterone continues to stabilise the lining of the uterus and readies it for implantation of a fertilised egg.
• If the egg is not fertilised, it will not implant and progesterone is no longer produced. Without progesterone, the lining of the thickened uterus begins to shed and leads to menses. Thus, one cycle ends and another begins.