Perimenopause marks the interval in which your body begins its transition into menopause. Perimenopause encompasses the years leading up to menopause — anywhere from two to eight years — plus the first year after your final period. It's a natural part of aging that signals the ending of your reproductive years.

Your estrogen level rises and falls unevenly during perimenopause. Your menstrual cycles may lengthen or shorten, and you begin having menstrual cycles in which you don't ovulate. It's only during cycles when you do ovulate that you can become pregnant.

When perimenopause starts and how long it lasts varies. You'll probably notice signs of impending menopause, such as menstrual irregularity, sometime in your 40s. But some women notice changes as early as their mid-30s.

Perimenopause causes some subtle — and some not-so-subtle — changes in your body. Some things you might experience include:

• Menstrual irregularity. As ovulation becomes more erratic, the intervals between periods may be longer or shorter, your flow may be scanty to profuse, and you may skip some periods.
• Hot flashes and sleep problems. About 65 to 75 percent of women experience hot flashes during perimenopause. Their intensity, duration and frequency vary. Sleep problems are often due to hot flashes or night sweats, but sometimes sleep becomes erratic even without them.
• Mood changes. Some women experience mood swings, irritability or depression during perimenopause, but the cause of these symptoms may be sleep disruption or other menopausal symptoms rather than the hormonal changes of menopause.
• Vaginal and bladder problems. When estrogen levels diminish, your vaginal tissues may lose lubrication and elasticity, making intercourse painful. Low estrogen levels may also leave you more vulnerable to urinary or vaginal infections. Loss of tissue tone may contribute to urinary incontinence.
• Decreasing fertility. As ovulation becomes irregular, your ability to conceive decreases. However, as long as you're having periods, pregnancy remains a possibility. If that's not what you want, use birth control until you've had no periods for 12 months.
• Changes in sexual function. During perimenopause, sexual arousal and desire may change. But for most women who had satisfactory sexual intimacy before menopause, this will continue through perimenopause and beyond.
• Loss of bone. With declining estrogen levels, you start to lose bone more quickly than you replace it, increasing your risk of osteoporosis.
• Changing cholesterol levels. Declining estrogen levels may lead to unfavorable changes in your blood cholesterol levels, including an increase in low-density lipoprotein (LDL) cholesterol — the "bad" cholesterol — which contributes to an increased risk of heart disease. At the same time, high-density lipoprotein (HDL) cholesterol — the "good" cholesterol — decreases in many women as they age, which also increases the risk of heart disease.

When to see a doctor
Some women seek medical attention for their perimenopause symptoms. But others either tolerate the changes or simply don't experience symptoms severe enough to warrant attention. Because subtle symptoms may come on gradually, you may not realize at first that they're all connected to the same thing — declining and fluctuating levels of estrogen and progesterone.

If you do experience symptoms that interfere with your life or well-being, such as hot flashes, mood swings or changes in sexual function that concern you, see your doctor.

As you go through the menopausal transition, your body's production of estrogen and progesterone fluctuates. These hormonal fluctuations are at the root of the changes your body goes through during perimenopause.

Menopause is a normal phase in a woman's life. But in some women, it may occur earlier than in others. Although not always conclusive, some evidence suggests that certain factors may predispose you to entering perimenopause at an earlier age, including:

• Smoking. The onset of menopause occurs one to two years earlier in women who smoke, compared with women who don't smoke.
• Family history. Women tend to experience menopause around the same age as their mothers and sisters, although the link between family history and age at menopause is still inconclusive.
• Never having delivered a baby. Some studies show that never having had a baby may contribute to early menopause.
• Childhood cancer treatment. Treatment for childhood cancer with chemotherapy or pelvic radiation therapy has been linked to early menopause.
• Hysterectomy. A hysterectomy that removes your uterus, but not your ovaries, usually doesn't cause menopause. Although you no longer have periods, your ovaries still release eggs. But such an operation may cause menopause to occur earlier than average.

Irregular periods are a hallmark of perimenopause. Most of the time, this is normal and nothing to be concerned about. However, see your doctor if:

• Bleeding is extremely heavy — you're changing tampons or pads every hour
• Bleeding lasts longer than eight days
• Bleeding occurs between periods
• Periods regularly occur less than 21 days apart

Signs such as these may indicate the presence of an underlying gynecological problem that requires diagnosis and treatment.

You'll probably start by discussing your symptoms with your primary care provider. If you aren't already seeing a gynecologist, your doctor may refer you to one.

What you can do
By monitoring your menstrual cycle and recording your signs and symptoms for several months, you'll gain a better understanding of the changes occurring during perimenopause. You'll also have valuable information to share with your doctor.

Appointments can be brief. To make the best use of the limited time, plan ahead and make lists of important information, including:

• Detailed descriptions of all your symptoms
• Names and dosages of all medications you take, including nonprescription drugs and supplements
• Questions for your doctor, such as what treatment options are available

Questions your doctor may ask
To facilitate a discussion about your perimenopausal experience, your doctor may ask questions such as:

• Do you continue to have menstrual periods?
• What symptoms are you experiencing?
• How long have you experienced these symptoms?
• How much distress do your symptoms cause you?
• What medications or vitamin supplements do you take?

Perimenopause is a process — a gradual transition. No one test or sign is enough to determine if you've entered perimenopause. Your doctor takes many things into consideration, including your age, menstrual history, and what symptoms or body changes you're experiencing. Some doctors may order tests to check your hormone levels. But other than checking thyroid function, hormone testing is rarely necessary or useful to evaluate perimenopause.

Possible therapies to treat perimenopausal symptoms include:

• Oral contraceptives. These are often the most effective treatment to relieve perimenopausal symptoms — even if you don't need them for birth control. Low-dose pills can regulate periods and reduce hot flashes and vaginal dryness.
• Progestin therapy. If you have irregular periods, but you can't — or choose not to — use oral contraceptives, cyclic progestin therapy may regulate your periods. Some women with heavy bleeding during perimenopause may find relief from a progestin-containing intrauterine device (IUD).
• Endometrial ablation. Endometrial ablation may provide relief from the heavy bleeding some women experience during perimenopause. During the procedure, the lining of the uterus (endometrium) is destroyed using a laser, electrical energy or heat, which effectively reduces menstrual flow or ends menstruation. This procedure isn't the right choice for everyone, so talk with your doctor about what is best for you.

Making healthy lifestyle choices may help ease some of the symptoms of perimenopause as well as promote good health as you age. These choices include:

• Good nutrition. Because your risk of osteoporosis and heart disease increases at this time, a healthy diet is more important than ever. Adopt a low-fat, high-fiber diet that's rich in fruits, vegetables and whole grains. Add calcium-rich foods or take a calcium supplement. Avoid alcohol and caffeine, which can trigger hot flashes.
• Regular exercise. Regular physical activity helps prevent weight gain, improves your sleep, strengthens your bones and elevates your mood. Try to exercise for 30 minutes or more on most days of the week.
• Stress reduction. Practiced regularly, stress reduction techniques, such as meditation or yoga, can promote relaxation and good health throughout your lifetime, but may be particularly helpful during the menopausal transition.