Remember when you were 13 and your girlfriends shared their complaints of menstrual aches and pains with you? Around that time, you probably realized that not everyone's periods were the same. Some got on a regular schedule pretty quickly, while others were so erratic they never knew when their "friend" was going to surprise them. Others were constantly popping aspirin for cramps, while a few were really troubled by PMS, making them difficult to live with for about a week each month. In some respects, menopause is back to the future: many of the same experiences, with a lot of individual variation.
As the name implies, natural menopause starts without your intervention; that's why it's sometimes called "spontaneous." You might detect subtle hints of what's coming 10 years or more before your periods stop. Your periods may become shorter and come closer together as the follicles (egg sacs) in your ovaries produce less progesterone. (This shortens the period of time when the uterine lining thickens in preparation for a fertilized egg.) Over time, the number and quality of your follicles diminish to the point where there's not enough estrogen produced to prompt ovulation each month. That's when your periods become more unpredictable. Some women experience problems like hot flashes or night sweats, sleeplessness, less lubrication when sexually aroused and moodiness as their hormone levels become increasingly erratic. You might go a few months without a period, and then get one again. Or you might have normal periods until the day they stop, and never start again. You won't know you've reached menopause until you go a year without a period. It's considered normal if this happens any time between the ages of 40 and 58, although the average in the industrialized world is 51.4 years. Exactly when it happens is a result of genetics and lifestyle.
Menopause doesn't always come naturally. Induced menopause occurs as a result of some outside intervention such as chemotherapy or pelvic radiation. The most common type of induced menopause is brought on by surgery, when both ovaries are removed. As a result, your body's main source of natural estrogen disappears immediately. This abrupt drop in hormones increases the likelihood that you'll experience more severe menopausal symptoms such as hot flashes and verbal memory problems. Premature (or early) menopause refers to any type of menopause (spontaneous or induced) that occurs before age 40. (Typically, premature menopause happens between ages 27 and 30.) While rare, early menopause puts women at greater risk for bone loss and heart disease.