Menstrual cycle: What's typical, what's not

Do you know when your last menstrual period began or how long it lasted? If not, it might be time to start paying attention.

When you track your menstrual cycles, you learn what's typical for you. You also can note when you ovulate and spot important changes, such as a missed period or unusual bleeding. Most changes aren't serious, but sometimes changes can signal a health issue.

The menstrual cycle is the monthly series of changes the body goes through to prepare for pregnancy. Each month, one of the ovaries releases an egg. This is called ovulation. Hormonal changes get the uterus ready for pregnancy. If the egg isn't fertilized, the lining of the uterus sheds through the vagina. This is a menstrual period.

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 24 to 38 days and last up to 8 days. When you first start having periods, your cycles may be longer. As you age, your menstrual cycles typically become shorter and more regular.

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.

Some kinds of birth control, such as extended-cycle birth control pills and intrauterine devices (IUDs), can change your cycle. Talk to your healthcare professional 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, talk with your healthcare team about any irregular bleeding around menopause since the risk of cancer of the uterus gets higher as you age.

To find out what's typical for you, use a calendar to record your period's start date each month. Track it for several months to identify the regularity of your periods.

If you're worried about your periods, also track the following every month:

• End date. How long does your period typically last? Is it longer or shorter than usual?
• Flow. Record the heaviness of your bleeding. Does it seem lighter or heavier than usual? How often do you need to change your tampon or pad? Have you passed any blood clots?
• Bleeding changes. Are you bleeding between periods?
• Pain. Describe any pain you have with your period. Does the pain feel worse than usual? It is not unusual to have some cramping or pain with your periods.
• Other changes. Have you noticed any changes in your mood, behavior or weight? Did anything new happen around the time you noticed changes in your periods?

Many things can cause irregular periods, including:

• Pregnancy or breastfeeding. A missed period can be an early sign of pregnancy. Breastfeeding typically delays the return of your period after pregnancy.
• Eating disorders, extreme weight loss or too much exercising. Eating disorders, such as anorexia nervosa, extreme weight loss and higher physical activity can interrupt your period.
• Polyendocrine metabolic ovarian syndrome (PMOS). Polyendocrine metabolic ovarian syndrome used to be called polycystic ovary syndrome (PCOS). People with this common condition may have irregular periods. They also can have enlarged ovaries that contain small collections of fluid, called follicles, located in each ovary. These follicles can be seen during an ultrasound exam. People who have PMOS often have more follicles in the ovaries than other people.
• Premature ovarian failure. Premature ovarian failure refers to the loss of typical ovarian function before age 40. People who have this condition, also known as primary ovarian insufficiency, might have irregular or occasional periods for years.
• Pelvic inflammatory disease (PID). This infection of the reproductive organs can cause irregular menstrual bleeding.
• Uterine fibroids. Uterine fibroids are growths in the uterus that are not cancer. They can cause heavy and prolonged menstrual periods.

Sometimes, birth control pills can help make an irregular menstrual cycle more regular. Birth control devices that progestin can make periods less heavy and ease cramping. Treating underlying issues, such as eating disorders, may help. But some irregularities can't be prevented.

Talk with your healthcare team if:

• Your periods suddenly stop for more than 90 days and you're not pregnant.
• Your periods become irregular after having been regular.
• You bleed for more than eight days.
• You bleed more heavily than usual or soak through more than one pad or tampon every hour or two.
• You have blood clots larger than a quarter in your menstrual flow.
• Your periods are less than 24 days apart or more than 38 days apart.
• You bleed between periods.
• You develop severe pain during your period.
• You suddenly get a fever and feel sick after using tampons.

Remember, tracking your period helps you know what's typical for you and what isn't. If you have questions or concerns about your menstrual cycle, talk to your healthcare professional.