Irregularity in the menstrual cycle
Menstrual cycles vary in length from one woman to another. They may occur at the same time each month or be irregular. Typically, a cycle occurs about once a month, but can be as short as 21 days or as long as 35 days and still be considered normal. Menstrual flow lasts about 3 to 7 days. A menstrual period is considered late if it is 5 or more days overdue according to the usual pattern of periods. A period is considered missed if there is no menstrual flow for 6 or more weeks.
What is the cause?
A late or missed period could be because of any of the following:
Pregnancy
This is the most common cause of missed periods. If you have had unprotected sex even once in the past several months, see your doctor for a pregnancy test before you consider any of the other possible causes.
Stress
Stress is the second most common cause of late or missed periods in teenagers. It may be emotional stress or depression. Or it may be physical stress, such as a severe illness, a sexually transmitted infection, 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 a vacation may also cause your period to be late or missed.
Normal development
During the first couple of years of menstruation many teenagers have irregular periods. During this time the body's hormones are not yet finely tuned, so the ovaries may not release an egg once every month. As a result, your cycles may be irregular, occurring as close together as 2 weeks or as far apart as 3 months.
Hormone imbalance
Hormone imbalance is rarely the cause of missed periods. In teenagers, polycystic ovary syndrome is the most common type of hormone imbalance that affects the menstrual cycle. Polycystic ovaries may cause irregular cycles, increased body hair, acne, and weight gain. Sometimes when you stop taking birth control pills you may have a temporary hormone imbalance and loss of periods. If you are having sex, be sure to use another reliable method of birth control because you could still become pregnant. Problems of the thyroid gland, pituitary gland, adrenal glands, or ovaries can be rare causes of irregular periods.
How to know what the cause is?
Pregnancy: A positive pregnancy test is the only way to be certain of pregnancy. It is best to see your doctor for a pregnancy test.
Stress: Some stress is a normal part of daily life. Only you can know if you are under too much stress.
Normal development: If your doctor finds nothing abnormal during your physical examination and you've been having periods for 2 years or less, your irregular periods may be part of your normal development. If you have had sexual intercourse, go to your doctor's office for a pregnancy test when your period is late for you, even if you normally have irregular cycles.
Hormone imbalance: If you have missed several periods without an explanation, your doctor can check your ovaries and look for any signs of hormone imbalance. Blood tests can be done to measure hormone levels.
When will periods return to normal?
It is important to identify pregnancy early so that you can discuss the options available to you and start prenatal care. Early prenatal care helps ensure a healthy baby. If the irregularity is due to stress then your periods should return when the activities or situations that are stressing you are eliminated or changed. As part of normal development, most girls' menstrual cycles become fairly regular as their hormone levels become mature and synchronized. A few women will continue to have irregular cycles as their normal pattern. Most often the doctor can treat a hormone imbalance, once the cause is discovered.
