Absent or irregular periods are periods that do not happen at all or that happen less than 6 to 8 times a year. If you do not get your period for a while, it could be because you are pregnant. Or there might be another reason, such as a medical condition.

Absent or irregular periods can be caused by:

  • Pregnancy
  • PCOS (which stands for “polycystic ovary syndrome”) – PCOS is the most common cause of irregular periods. In people with this condition, the ovaries make too much male hormone. This can disrupt monthly periods and cause excess facial hair, acne, and problems with weight.
  • A decrease in your body’s energy supply – This can result from exercising too much, being very stressed, having an eating disorder, or burning more calories than you take in.
  • Too much prolactin – Prolactin is a hormone made in the “pituitary gland”, which is a small organ at the base of the brain.
  • Early or premature menopause – Menopause is the time when a person naturally stops having periods. This normally happens between the ages of 45 and 55. But in some people, it happens earlier. Doctors use the term “early menopause” in people who go through menopause between the ages of 40 and 45 years. For people younger than 40, doctors use the term “premature menopause.”
  • Certain types of hormonal birth control – Some forms of birth control can cause absent or irregular periods. This is most common with those that contain only the hormone progestin. Examples include the progestin-only pill (sometimes called the “minipill”), the implant, and hormone-containing intrauterine devices (IUDs). It is also common with birth control pills that have a lower dose of estrogen. It does not mean the pill is not working, as long as you are taking it every day.
    If you take birth control pills and use “continuous dosing,” you will also not get a monthly period. Continuous dosing means skipping the hormone-free pills that come with your prescription, and taking hormone pills every day instead.

See your doctor or nurse if:

  • You are older than 15 and still have not had your period
  • You used to get periods, but you have not had a period for more than 3 months
  • Your periods happen more than 45 days apart

Make sure to tell your doctor if you:

  • Think you might be pregnant
  • Have family members with irregular periods
  • Have bad acne or hair on your chest or face
  • Have gained weight and are having trouble losing it
  • Have hot flashes, which feel like a wave of heat that starts in your chest and face and then moves through your body
  • Have night sweats, which are hot flashes that happen when you are asleep
  • Have new headaches or trouble seeing
  • Notice milky fluid coming out of your breasts
  • Are under lots of stress
  • Have recently lost weight
  • Are exercising more than you used to
  • Have changed how much you eat or what kinds of foods you eat
  • Are taking any medicines, herbs, or vitamins

Your doctor or nurse will decide which tests you should have based on your age, other symptoms, and individual situation.
Here are the most common tests doctors use to find the cause of absent or irregular periods:

  • Pregnancy test – Pregnancy is a common cause of missed periods. Your doctor will want to find out if you are pregnant before doing any other tests.
  • Blood tests – These measure hormones that affect the reproductive system.
  • Pelvic ultrasound – This test uses sound waves to make a picture of your uterus, cervix, and vagina (figure 1). The picture can show if there is something wrong with these organs.
  • MRI – This test uses a large magnet to make detailed pictures of the brain. It can show if there is a problem in the part of the brain that controls the body’s hormones. An MRI might be done if blood tests are abnormal.

That depends on what is causing your missed periods, and on whether you want to get pregnant. Possible treatments include:

  • Birth control pills to make periods regular
  • Losing weight if you are overweight
  • Medicines to help you get pregnant if you are having trouble getting pregnant on your own
  • Changing the way you eat and exercise, such as:
  • Eating more calories
  • Gaining weight if you weigh too little (calculator 1)
  • Easing up on exercise, if you exercise a lot
  • Reducing stress
  • Hormones to treat hot flashes (if you are going through early menopause)
  • Medicines to lower prolactin levels (if your pituitary gland is making too much prolactin)

You can reduce your chances of missing periods by eating well and staying at a healthy weight. Being too thin or too heavy can cause irregular periods.