Menopause, when it occurs between the ages of 45 and 55, is considered "natural" and is a normal part of aging. But, some women can experience menopause early, either as a result of a surgical intervention (such as removal of the ovaries) or damage to the ovaries (such as from chemotherapy). Menopause that occurs before the age of 45, regardless of the cause, is called early menopause. Menopause that occurs at 40 or younger is considered premature menopause.