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Menstrual Period, Late or Missed

How long does a normal menstrual cycle last?

A menstrual cycle is the time from the day a menstrual period starts to the time the next period starts. The average menstrual cycle is 28 days long. However, a normal cycle can be shorter or longer than this. It may be anywhere from 21 to 35 days long. Most periods last 3 to 5 days, but anywhere from 2 to 7 days is normal. Menstrual cycles may happen around the same date every month or they may be irregular.

When is a period late?

A menstrual period is considered late if it hasn’t started 5 or more days after the day you expected it to start. A period is considered missed if you have had no menstrual flow for 6 or more weeks after the start of your last period.

What is the cause?

During the first couple of years of menstruation many teenagers have irregular periods. During this time your body is still developing and the ovaries may not release an egg every month. As a result, your cycles may be irregular, occurring as close together as 2 weeks or as far apart as 3 months. If you have been having periods for 2 years or less and your physical exam is normal, your irregular periods may be part of your normal development.

Most girls' menstrual cycles become fairly regular as their hormone levels mature and synchronize. A few women will continue to have irregular cycles as their normal pattern.

Other causes of a late or missed period are:

  • Pregnancy
  • Stress
  • Hormone imbalance

Pregnancy

Pregnancy is the most common cause of missed periods in teenage girls. If your period is late and you have had sex even once in the past several months, see your healthcare provider. It’s best to see your healthcare provider for a pregnancy test because home test kits can be confusing and give incorrect or unclear results.

It is important to find out early if you are pregnant. Starting prenatal care right away helps you have a healthy baby.

If you are pregnant, you will not have a normal period until after the baby is born.

Stress

Stress is the second most common cause of late or missed periods in teenagers. It may be emotional stress (for example, breakup with a boyfriend or final exams) or depression. Or it may be physical stress to the body, such as a severe illness, a sexually transmitted disease, rapid weight loss or gain, or strenuous exercise. Dieting or binging and purging may interrupt menstrual cycles. Changes in your usual routine (for example, going on vacation) may also cause your period to be late or missed.

Some stress is a normal part of daily life. Too much stress for your body may cause a late or missed period. Your periods should come back when you change your activities or situation.

Hormone imbalance

In some cases hormone imbalance is causes missed periods. For example, if you have been taking birth control pills, your periods may be irregular for a while when you stop taking the pills. If you are having sex, be sure to use another reliable method of birth control because you could still get pregnant.

A rare problem called polycystic ovary syndrome can affect a young woman’s menstrual cycle. Polycystic ovaries may cause irregular cycles, more body hair, acne, and weight gain. It can be treated with hormone medicine prescribed by your healthcare provider.

Problems of the thyroid gland, pituitary gland, adrenal glands, or ovaries are other rare causes of irregular periods.

How can I take care of myself?

  • Mark on a calendar the dates when each period starts and stops. This information can help your healthcare provider make a correct diagnosis. Take the calendar to your appointment.
  • Eat healthy foods and keep your weight steady.
    • If you are overweight, a balanced diet and regular exercise will help you lose weight slowly. It’s best to lose no more than 2 pounds a week.
    • If you are underweight, make sure you are getting enough nutrition.

    Talk with your healthcare provider if you are not sure what your proper weight should be, or if others are worried about your weight. A nutritionist may also be able to give you helpful advice.

  • If you follow a strenuous exercise program, consider cutting back until your periods come back. If you don’t want to cut back on your exercise, see your healthcare provider to see if you need to cut back on exercise, eat more calories, or need treatment.
  • If you have sex, always use birth control. Talk to your healthcare provider about your choices.
  • If you have had sex, get a pregnancy test if your period is 5 or more days late. Don't wait. You can get confidential testing and counseling in most healthcare providers’ offices and clinics.
  • See if you can get some counseling if you are feeling stressed out.
Developed by RelayHealth.
Pediatric Advisor 2013.4 published by RelayHealth.
Last modified: 2013-01-28
Last reviewed: 2012-08-05
This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.
Copyright ©2013 McKesson Corporation and/or one of its subsidiaries. All rights reserved.
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