What is a period and why do periods happen?

Menstruation, or a period, is normal and expected bleeding that occurs as part of a regular monthly cycle. It all starts in your brain, where a small gland called the pituitary makes two hormones -- follicle stimulating hormone and luteinizing hormone. These hormones act as signals to your ovaries (two almond-sized organs in your pelvis) to make other hormones, including estrogen and progesterone. Estrogen and progesterone send signals to the lining of your uterus to grow thicker. When these hormone levels fall, the thickened lining of the uterus gets loose and eventually comes out through the vagina – and this is a period, or menstruation.

When do periods start?

Every person has their own schedule – there’s no one “right” age. For many adolescents, periods start around 12 to 13 years old. but may start as young as age nine or as late as age 14. They usually start about two years after breasts begin to develop. If you don’t get a period by the time you are 15 years old, or three years after your breasts start to grow, it’s a good idea to talk to your health care provider.

How often do periods happen?

Periods can be irregular for the first one to two years after they start. From the first day of one period to the first day of the next period is usually between 21 and 45 days, but can be shorter or longer in younger teens.

The ovaries hold hundreds of thousands of eggs. As teens go through puberty, the ovaries begin to release an egg about once each month. This is known as ovulation. The process of ovulation causes levels of estrogen and progesterone to rise and fall more regularly, so periods become more regular.

It’s a good idea to track your periods using a calendar or app on your phone. If you get your period more often than every three weeks, or if you go more than three months without getting a period, you should talk to your health care provider about it.

Hormone imbalances like in thyroid disease or polycystic ovarian syndrome are common causes of irregular periods. Weight loss and eating disorders can also cause irregular periods, or cause periods to stop happening. If you are sexually active, irregular periods can also be a sign of pregnancy or of sexually transmitted infections.

Is it normal to have cramps with your period?

It’s normal to have mild cramping at the start of your period. But if your pain is not helped by over the counter medication, or causes you to miss school, activities, and time with friends, this is not normal.

For most teens, painful periods are caused by something called “primary dysmenorrhea.” This means pain related to the period itself and not an underlying problem. If you are having painful periods you should talk with your health care provider. You do not need to suffer; there are treatments that can help.

How long do periods last and how heavy is too heavy?

For most teens, periods last between two and seven days. Teens typically use between three and six pads or tampons per day. If you are bothered by how long or heavy your periods are, be sure to talk with your health care provider.

Your period may be too heavy if you are:

  • soaking through a pad or tampon every one to two hours or more.
  • having periods that last more than seven days.
  • passing clots the size of a quarter or bigger in your period.
  • regularly leaking onto your clothes or your bed.
  • missing school and other activities because your period is too heavy.

There are different reasons why teens may get heavy periods. Hormonal imbalance may be one cause. Bleeding disorders are another common cause. Signs of bleeding disorders include:

  • easy bruising or bruising without a known injury
  • frequent nosebleeds lasting more than 15 minutes
  • bleeding when you brush your teeth
  • bleeding after surgery or dental work
  • having a family member with a bleeding problem

Be sure to tell your health care provider if you are experiencing any of these symptoms.

What happens if my periods are too heavy?

If your periods are too heavy, it will be important to talk with your health care provider so they can work with you to understand why. Heavy periods can also cause in serious health problems like anemia (low red blood cell count) and iron deficiency, so it will also be important to test for these, too.

There are different treatment options to help with heavy periods. These include hormonal therapies (like birth control pills, shot, patch, ring, implant, or intrauterine device) and/or therapies targeting the bleeding problem (antifibrinolytics, DDAVP, factor products). Your health care provider can work with you determine which will work best for you. Anemia and iron deficiency are treated with iron supplementation or infusion. Severe anemia is sometimes treated with blood transfusions.

The evaluation and treatment of heavy periods in teens often requires coordinated care from multiple services. Here at Hasbro Children’s Hospital and the Tomorrow Fund Clinic, we have established a combined Pediatric Hematology and Adolescent Medicine Clinic to help evaluate and treat young people with heavy periods. Our clinic includes pediatric hematology, adolescent medicine, nursing, and social work, all working together to evaluate and treat our patients. If you would like to be seen in our clinic, please talk with your primary care provider or call us at 401-444-5241.

If you would like to see a specialist for other period concerns, please talk with your primary care provider or call the Adolescent Medicine Clinic at 401-444-5980.

Salley Pels, MD and Emily Allen, MD

Dr. Salley Pels is a pediatric hematologist/oncologist and director of the Hemostasis and Thrombosis Center at Rhode Island Hospital.

Dr. Emily Allen is a board-certified pediatrician and a member of the adolescent medicine team at Hasbro Children's Hospital.