Menopause usually occurs sometime between age 45 and 55, but the average age is 51, according to the National Institute on Aging (NIA) and the American College of Obstetricians and Gynecologists (ACOG). Menopause means the permanent end 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 have them for 2 to 5 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 with your healthcare provider about what you can do to help prevent bone loss.

Used for a short time, hormone therapy can help relieve symptoms of menopause. Long-term use, though, raises the risk for breast cancer, heart attack, and stroke.

A woman who doesn’t want to get pregnant should continue to use birth control for at least a full 12 months after her last period, the NIA says.