Heavy flow means losing more menstrual blood than is normal. A normal menstrual period requires us to change two soaked normal-sized sanitary products (vaginal pads, tampons) two to four days a cycle or to empty a menstrual cup of a teaspoon (5 millilitres, ml) of blood twice a day for two to four days in a period. Normal cycles last from three to six days; heavy flow usually, but not always, lasts longer than seven days. Women often describe heavy flow as "flooding," or "clotting" and requiring that they change sanitary products every couple of hours during the day.
The official definition of heavy flow is loss of 80 ml or more blood in one menstrual period since that amount of blood loss causes iron-loss anemia in 80 of 100 women. Since 5 ml is a teaspoon and a soaked usual-sized tampon/pad holds about that much, heavy flow means losing 16 teaspoons or soaking 16 normal-sized pads/tampons (or emptying a full 30-ml menstrual cup almost three times) in one whole period.
Heavy flow is usually caused by too much estrogen (that makes the lining of the uterus grow very thick and fragile) and too little progesterone (whose job is to control endometrial growth and make it stronger). Heavy flow is most common in the teen years and in perimenopause when it is experienced by at least 25 of every 100 women. The good news is that simply taking one tablet of ibuprofen (over the counter, non-steroidal anti-inflammatory) (200 mg is the usual-sized tablet) with each meal will decrease heavy flow by a quarter to a half. Tell every woman you know! Read more about heavy menstrual flow here.