What's typical?

The menstrual cycle is counted from the first day of one period to the first day of the next. The cycle isn't the same for everyone. Menstrual bleeding might happen every 21 to 35 days and last 2 to 7 days. For the first few years after menstruation begins, long cycles are common. However, menstrual cycles tend to shorten and become more regular as people age.

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

Certain kinds of birth control, such as extended-cycle birth control pills and intrauterine devices (IUDs), will change a menstrual cycle. Talk to your health care provider about what to expect.

When you get close to the time when your menstrual cycles will end, called menopause, your cycle might become irregular again. However, the risk of cancer of the uterus gets higher as you age. Talk with your health care provider about any irregular bleeding around menopause.