Menopause is a natural biological process that begins when your body starts making less estrogen and progesterone as a result of changes in ovarian function.

Until recently, menopause was shrouded in misconceptions and myths. The scientific truth is that menopause is a natural biological process and a normal part of aging.

At birth, your ovaries contain as many as two million egg-containing follicles. As you mature and start ovulating, your follicle reserve steadily declines. When the supply is exhausted, your ovaries stop producing estrogen and progesterone, the sex hormones which have been responsible for regulating your periods over the years.

As menopause approaches, ovulation and estrogen production become erratic and may cause your periods to become irregular.  As estrogen levels drop, the level of follicle-stimulating hormone (FSH) rises, trying to stimulate your ovaries to produce more estrogen and maintain your menstrual cycle .

Rising levels of FSH can be a good indicator that you have started your transition into menopause. But day-to-day hormone levels are not a reliable indication of where you are in the menopausal transition. There are a number of physical symptoms, described below, that also serve as indicators that you are entering menopause.

Stages

Bear in mind that menopause is actually a multi-stage process that takes place over years, and the amount of time it takes to complete the process may vary widely from woman to woman.  While different health professionals may define the stages of menopause in different ways, the following descriptions will help you gain a better understanding of the process.

• Pre-menopause: Some people use pre-menopause and perimenopause interchangeably. Others use it to define the time when a woman is just starting to experience irregular periods but is showing no signs of classic menopausal symptoms, such as hot flashes or vaginal dryness. Still others use pre-menopause to describe a longer span of time prior to perimenopause, sometimes starting as early as your mid-30s.
• Perimenopause: Some define perimenopause as the transitional time before menstruation stops. Others extend the definition past your final menstrual period for one to two years. While the average timeframe for perimenopause is about four years, it can last up to ten years and still be considered normal.
• Menopause: Menopause refers specifically to the date of your last period. Doctors pinpoint your final period once you haven't had one for 12 months. This is the point when you no longer have periods or need to be concerned about getting pregnant. This term is commonly used to refer to the entire process - three of the four stages including perimenopause and post-menopause. Menopause also can occur suddenly with early failure of the ovaries, such as when a woman has her ovaries removed, or chemotherapy is used to fight cancer.
• Post-menopause: This stage begins with your final period and lasts the rest of your life. While the signs and symptoms of menopause diminish over a year or two, you are at increased risk for longer-term health problems (including osteoporosis) related to low estrogen, and you should work with your doctor to manage them.

Signs and symptoms

Although some women have no menopausal symptoms aside from their periods ending, most experience one of more of the following symptoms, many of which improve over time or can be treated under a doctor's care.

• Hot flashes
  Hot flashes - also known as hot flushes - are the most common early symptom when estrogen levels decrease. When less estrogen is secreted, your capillaries expand irregularly, causing hot sensations in the face, neck, and chest. You may experience hot flashes for a year or so, but symptoms can persist for five years or more. Irritation, impatience, anxiety, and worry may also accompany hot flashes.
• Night sweats and sleep disturbance
  Your usual sleep patterns may undergo dramatic changes because of night sweats, which are brought on by hot flashes. You may awaken suddenly with soaking night sweats followed by chills. You may have trouble falling back to sleep or achieving a sound, restful sleep. Too little sleep may affect your mood and overall health.
• Changes in physical appearance
  Following menopause, fat that once was concentrated in your hips and thighs may find a new home above your waist and in your abdomen. Other notable changes may include weight gain, a loss of fullness in your breasts, and thinning hair. And, even though your estrogen level has decreased, your body continues to produce tiny amounts of the male hormone testosterone, which may result in the appearance of coarse hairs on your chin, upper lip, chest and stomach.
• Emotional changes/moodiness
  As you move through menopause, you may experience a number of emotional changes, including mood swings, irritability, anxiety, depression, sensitivity, fatigue, and forgetfulness. In the past, these symptoms were attributed primarily to hormonal fluctuations. Today we know that other factors may contribute to these mood changes. These include stress, insomnia, and life events such as the illness or death of a loved one, children leaving home, job loss, financial crisis, and retirement, which may also occur at this stage in a woman's life.
• Decreased fertility
  When ovulation begins to fluctuate, you are less likely to become pregnant. Until you stop ovulating, however, pregnancy is still possible.
• Decreased sex drive
  In addition to losing their ability to secrete estrogen, the ovaries no longer produce testosterone - the hormone responsible for sex drive in both men and women. Some women's bodies may still produce the tiny amount needed through the adrenal glands. 
• Irregular menstruation
  Your menstrual cycle may stop suddenly, or gradually get lighter or heavier and then stop. The irregularity of your periods may be your first signs that menopause is approaching.
• Vaginal changes
  As your estrogen level falls, the tissues lining your vagina and urethra - the opening to your bladder - tend to become drier, thinner and less elastic. The decrease in lubrication may cause you to experience burning or itching. You may also be more susceptible to infections of your urinary tract or vagina. These changes may also make sexual intercourse uncomfortable or even painful.
• Loss of bone mass
  Women lose an average of 25% of their bone mass from the time of menopause to age 60, due in large part to the loss of estrogen. Over time, this loss of bone may lead to osteoporosis, a "brittle-bone" disease that contributes to bone fractures.
• Increased risk of heart disease
  Lower levels of estrogen put you at greater risk for heart disease and stroke.
  A high fat diet, cigarette smoking, high blood pressure, high cholesterol, physical inactivity and obesity increase your risk.
• Skin ages faster
  After menopause, skin loses elasticity, causing more wrinkles. Although the lack of estrogen is not the main cause, hormone treatment may help the skin maintain elasticity. Also, if you previously experienced adult acne, you may notice that the condition worsens.
• Breast changes
  The lack of estrogen affects breast size and supporting tissue. After menopause, breasts may stretch, decrease in size, or soften because there is less connective tissue and less glandular tissue.
• Urinary tract changes
  With the thinning of the lining of the urethra and the weakening of surrounding pelvic muscles, you may experience the need to urinate more frequently. Other symptoms may include frequent bladder infections, painful urination, sudden urinary urgency, and frequent urination during the night. Urinary incontinence may also become a problem. See Second Opinion Incontinence and Urine Leakage episode for more information.