Abnormally heavy bleeding is when you suddenly experience heavy or significantly heavier bleeding than what your normal menstrual flow "pattern" is. Clinically, abnormally heavy menstrual bleeding is defined by more than 80 cc of blood lost per cycle. However, studies show that many women who complain of an abnormally heavy flow have lost much less than that. Your own perception of what's heavy is more important than your doctor's perception, and good doctors will try to get you to describe your impression of "heavy" and compare it with your normal pattern. If a doctor tries to determine exactly how much blood you have, this is a waste of time for both of you. A more scientific measurement is to simply take inventory of the number of pads or tampons you're going through and compare that with your normal pattern.

Why is it suddenly so heavy?

Age has a lot to do with menstrual flow. In fact, teenage women and women approaching menopause will have similar cycles, often characterized by changes in flow. Women between twenty and forty will (or should) have regular patterns that do not fluctuate that much from period to period.

If you're under twenty and notice heavy bleeding, ask your doctor to check for a blood coagulation disorder known as van Willebrand's disease or platelet disorders, such as thrombocytopenia or thromboasthenia. Most of the time, however, abnormally heavy bleeding is caused by some sort of hormonal disorder, which can be investigated by a reproductive endocrinologist.

If you're over forty, abnormally heavy bleeding is usually caused by what's known as the "anovulatory period." In this case, you make estrogen during the first part of your cycle, but for some reason (often unknown) you just don't ovulate.

Therefore, you don't produce progesterone and you develop an unusually thick uterine lining, which is expelled during your period. This translates into abnormally heavy bleeding.

No matter how old you are, one of the chief culprits of abnormally heavy bleeding in women is often high doses of ASA (aspirin). So, if you're fighting off headaches or other ailments before your period, you may want to use an alternative pain reliever. Sometimes your contraception method can affect your menstrual cycle. For instance, an IUD (intrauterine device) or hormonal contraception can sometimes trigger heavy bleeding. Changes in exercise patterns (usually decreased exercise) can also affect your menstrual flow.