Menopause usually occurs sometime between age 45 and 55, but the typical age is 50, according to the National Institute on Aging (NIA). Menopause means the permanent cessation of menstruation.

Menopause begins at that point when you have had your last menstrual cycle, the NIA says. You won't know whether you have had your last period until you have been period-free for one year.

If you smoke, you may go through menopause about 1-1/2 years earlier than women who don't smoke, the NIA says.

Hot flashes can occur several times an hour, a few times a day or once or twice a week, the NIA says. Most women have hot flashes for about a year. Some may experience them for two to five years.

The pituitary gland releases this hormone to stimulate the ovaries to release follicles, or eggs. A blood test that measures the hormone, along with symptoms such as hot flashes and period cessation, confirms perimenopause -- the stage just before menopause.

Bones thin when ovaries stop producing estrogen. Cholesterol levels can rise, which threatens heart health.

Talk to your health care provider about what you can do to help prevent bone loss.

Progesterone makes the uterus shed its lining, which helps protect against endometrial cancer. There is concern that estrogen and breast cancer may be linked, and a national panel has recommended that estrogen be listed as a cancer-causing agent.

A low dose can help treat hot flashes and help prevent osteoporosis.