Natural and expected hormone changes cause perimenopause, menopause, and postmenopause.

Perimenopause

As you age, your body begins the natural sequence of changes that eventually bring an end to your menstrual cycle (menopause). The number and quality of your eggs decline, hormone levels fluctuate, and your menstrual cycle becomes less predictable. This time of unpredictable change is called perimenopause.

Menopause and postmenopause

After a few years of fluctuating hormones, your estrogen and progesterone levels begin to decline. When your estrogen drops past a certain point, your menstrual cycle and your ability to become pregnant end. After 1 year with no menstrual bleeding, you reach menopause and begin postmenopause.

A year or more into postmenopause, estrogen levels typically even out at a low level. Since estrogen also plays a role in other functions of your body, its decline has far-reaching effects, including faster bone loss and drying and thinning of the skin and the vaginal and urinary tracts.

Menopause can be caused suddenly and prematurely by surgical removal of the ovaries (oophorectomy), by chemotherapy, or by radiation therapy to the abdomen or pelvis.

Causes of early menopause

Your body has its own timeline for when menopause will start and how long it will last. In fact, it's likely that your timeline will be much like your mother's was. However, certain lifestyle choices and medical treatments can cause or are linked to an earlier menopause, including:

• Smoking. On average, women who smoke reach menopause 1.5 years earlier than those who don't. The longer you have smoked and the more you smoke, the stronger this effect is likely to be.⁴
• Radiation therapy to or removal of the pituitary gland.
• Chemotherapy.
• Radiation therapy or other treatment to the abdomen or pelvis that damages the ovaries so that they no longer function.
• Genetic and autoimmune diseases.
• Removal of both ovaries (oophorectomy), which causes sudden menopause.
• Living at high altitudes.⁴
• A vegetarian diet.⁴
• Low body fat (body mass index of 25 or less).