What is missed or irregular periods?

Menstrual periods often occur every 21 to 35 days. But you may be different. Missed or irregular periods must be looked at in terms of what is normal for you.

Menstrual periods often aren't regular during the first few years after your period starts. It may take several years for the hormones that control menstruation to reach a balance.

Periods also may not be regular when you get closer to perimenopause and menopause. Menopause occurs when it has been 12 months since you had a period.

Pregnancy is the most common cause of a missed period. If you might be pregnant, treat yourself as if you are pregnant until you know for sure. Use a home pregnancy test as the first step to find out if you are pregnant.

If you aren't pregnant, other causes of missed or irregular periods include:

• Excessive weight loss or gain. Low body weight is a common cause of missed or irregular periods. Obesity also can cause menstrual problems.
• Eating disorders, such as anorexia or bulimia.
• Increased exercise. Missed periods are common in endurance athletes.
• Emotional stress.
• Chronic diseases, such as diabetes or irritable bowel syndrome.
• Medicines such as birth control methods. These may cause lighter, less frequent, more frequent, or skipped periods or no periods at all.
• Hormone problems, such as polycystic ovary syndrome. They may cause a change in the levels of the hormones that the body needs to support menstruation.
• Illegal drug use.
• Problems with the pelvic organs, such as an imperforate hymen or Asherman's syndrome.
• Breastfeeding. Regular periods may not resume until after you have finished breastfeeding.
• Primary ovarian insufficiency. This means you stop having periods before age 40. It can be caused by surgery, chemotherapy, or radiation therapy to the belly or pelvis.

Remember, you can still become pregnant even though you don't have periods. Practice birth control if you don't wish to become pregnant.

If you've skipped a period, try not to worry. It isn't uncommon to miss periods now and then. Unless you're pregnant, your cycle likely will return to normal next month.

Here are some ways to care for yourself when you have missed or irregular periods:

• Eat a balanced diet. Being underweight or overweight can cause missed and irregular periods.
• If you are an endurance athlete, you may have to cut back on your training or increase your calorie intake. Stress and low body fat are thought to contribute to missed or irregular periods in athletes. Be sure to talk with your doctor about hormone and calcium supplements to protect against bone loss if you are missing periods.

If you think you might be pregnant

Do a home pregnancy test if you've had sex since your last period. If the result is positive, practice the following good health habits until you see your doctor:

• Eat a balanced diet.
• Don't smoke or use other tobacco products.
• Don't use alcohol or drugs.
• Avoid caffeine, such as coffee, tea, or chocolate. Or limit your intake to about 1 cup of coffee or tea each day.
• To avoid the risk of toxoplasmosis, don't clean a cat litter box.
• Avoid people who are ill.
• Take a vitamin supplement that contains folic acid. Or take a prenatal vitamin.

If the home pregnancy test is negative but you still have pregnancy symptoms, it's a good idea to see your doctor to confirm the results. Practice good health habits until you see your doctor.