The menstrual cycle is the hormonal process that occurs each month to prepare the body
for a possible pregnancy.
For most teens, they have bleeding that comes every 21 to 45 days and lasts for 2 to 7 days
in a row.
This is called a menstrual period.
Menstrual periods are not normal if they last longer than 8 days in a row or if they are
coming more often than every 3 weeks.
Bleeding is considered too heavy if there are large blood clots that come out or if
a pad or tampon needs to be changed every hour to stop bleeding onto clothes.
Heavy menstrual bleeding may cause a person to feel really tired or dizzy or lose enough
blood that they have low iron levels or anemia.
In preteens and teens, heavy menstrual bleeding most often happens because the body is not
having regular ovulation which can lead to an imbalance of hormones.
At the beginning of puberty, the ovary makes a hormone called estrogen.
Estrogen causes the lining of the uterus to grow thicker.
Around the middle of the menstrual cycle, ovulation occurs.
This is when the ovary releases an egg.
Following ovulation, the ovary makes a second hormone called progesterone.
Progesterone causes the lining of the uterus to become mature and stabilize.
Over time, the lining of the uterus becomes thick enough that it causes menstrual bleeding.
For many teens, ovulation does not happen regularly in the first several years after
getting their first period.
Without monthly ovulation, the lining of the uterus grows thicker due to the presence of
estrogen without the balance of progesterone.
This may cause irregular, frequent, heavy and long periods.
Another reason that teens may have heavy menstrual periods is because of a bleeding disorder.
This means that their bleeding does not stop or clot normally and so they will bleed more
Unlike for adults, heavy periods in teens are not caused by problems like fibroids,
polyps or other growths.
Approximately 3 in 10 menstruating people experience heavy menstrual periods at some
point during their life.
This is even more common in teens.
As many as 8 in 10 teens have periods that are heavy or irregular.
Menstrual bleeding and cramping are the leading causes of missed school days in teens.
If you suffer from heavy bleeding and cramping, there are treatment options that are safe
and also work really well.
There are several hormonal medications that will prevent the lining from becoming too
Some examples are low dose birth control pills, the patch, or an intrauterine device.
If your blood counts or iron levels are low, a condition referred to as anemia, an iron
supplement will be recommended until these levels return back to normal.
These treatments are essential to help get teens back to a normal energy level, engage
in regular activities and to perform well in school.
When a bleeding disorder is found, our gynecology and hematology doctors work together to make
sure that there is a very good plan to control your bleeding.
At Children’s Hospital Colorado, our pediatric and adolescent gynecologists have expert training
in reproductive health problems and can help with common and rare causes of heavy menstrual
If you are experiencing heavy periods, please reach out to your parent or a healthcare provider.
With treatment, you can experience shorter and lighter periods that don’t interfere
with your school and other activities.