The menstrual cycle stops at the age of 45 to 50 years because of a natural decline in the number and quality of eggs in the ovaries. This process is called menopause. As women age, their ovaries produce fewer hormones, and the menstrual cycle becomes irregular and eventually stops. This is a natural part of the aging process and is influenced by genetics, lifestyle factors, and medical conditions. This transition can cause a range of symptoms, including hot flashes, mood changes, and vaginal dryness.

The term menopause is commonly used to describe the years when a woman's ovaries gradually begin to produce fewer eggs and less of the female hormones oestrogen and progesterone.

This reduction in hormone production causes periods to become less regular until they stop altogether, and produces physical and psychological symptoms in many women. Depending on the severity of symptoms and risk of developing other health conditions, treatment and/or lifestyle changes may be recommended.

Menopause is a normal part of ageing for a woman and literally means "last period". It is generally considered to be complete when a woman has not had a period for one year. Menopause, often referred to as "the change of life", usually occurs between the ages of 45 and 55 years. Premature (early onset) menopause is when periods stop before the age of 40 years.
Why does menopause occur?
At birth a woman's ovaries contain a lifetime supply of eggs. At puberty, the ovaries begin releasing eggs each month (ovulation). This prompts oestrogen and progesterone to be released by the ovaries, which in turn stimulate the lining of the uterus (endometrium) to thicken in preparation for the implantation of a fertilised egg. If an egg is not fertilised the endometrium is shed and a period occurs. This entire process is known as the menstrual cycle.

Menopause occurs when the ovaries fail to produce enough hormones to stimulate the monthly growth of the endometrium, and periods stop permanently.

The time frame from when symptoms first appear to when menopause occurs may be several years. This time frame is medically referred to as the climacteric or the perimenopause.

After menopause a woman's risk of coronary heart disease (including high blood pressure, heart attack and stroke) increases and becomes as high as it is for men. The risk of developing osteoporosis (bone thinning) is also increased.

There are three types of menopause:
Natural menopause occurs when levels of oestrogen and progesterone decline naturally.
Premature (early) menopause is when periods stop before the age of 40 years. This can be due to many reasons including medical conditions such as diabetes or underactive thyroid (hypothyroidism), and surgery or medications that have affected the blood supply to the ovaries. Genetic factors may also play a part as premature menopause can run in families. Women who smoke are also more likely to go through premature menopause. Sometimes, however, there is no identifiable cause.
Artificial (surgical) menopause is a consequence of surgical removal of both ovaries or destruction of the ovaries by some cancer treatments. With artificial menopause there is a sudden drop in hormone levels and menopausal symptoms begin abruptly. Often the symptoms experienced are more severe than those experienced with natural or premature menopause.