What's normal?

The menstrual cycle, which is counted from the first day of one period to the first day of the next, isn't the same for every woman. Menstrual flow might occur every 21 to 35 days and last two to seven days. For the first few years after menstruation begins, long cycles are common. However, menstrual cycles tend to shorten and become more regular as you age.

Your menstrual cycle might be regular — about the same length every month — or somewhat irregular, and your period might be light or heavy, painful or pain-free, long or short, and still be considered normal. Within a broad range, "normal" is what's normal for you.

Keep in mind that use of certain types of contraception, such as extended-cycle birth control pills and intrauterine devices (IUDs), will alter your menstrual cycle. Talk to your health care provider about what to expect.

When you get close to menopause, your cycle might become irregular again. However, because the risk of uterine cancer increases as you age, discuss any irregular bleeding around menopause with your health care provider.