How heavy is too heavy?
Nobody tells you the number. You are left comparing yourself to women who do not discuss it either, and the honest answer is that most of us have no idea what normal looks like. Here is the rule clinicians actually use, in words you can use at an appointment.
Five tests. Any one of them counts.
These are the criteria the CDC uses to define heavy menstrual bleeding. They are not a diagnosis of anything. They are the threshold at which bleeding stops being a private inconvenience and becomes something worth saying out loud.
The hour test.
Soaking through one or more pads or tampons every hour, for several hours in a row. If you are watching the clock to time a change, that is the answer.
The quarter test.
Passing blood clots larger than a quarter. Small clots are ordinary. Repeatedly passing ones that size is the single easiest thing on this list to check and the one women most often leave out.
The seven day test.
Bleeding for longer than seven days. Count from the first day of real bleeding, not from spotting.
The night test.
Having to get up to change protection overnight, or doubling up on protection to get through the day, or bleeding through to your clothes or your bedding.
Tiredness that does not lift, breathlessness on stairs you used to manage, or the pallor other people comment on before you notice it. Heavy bleeding over months can leave you low on iron, and feeling constantly exhausted is a symptom, not a personality trait.
Criteria: Centers for Disease Control and Prevention, Heavy Menstrual Bleeding. The American College of Obstetricians and Gynecologists uses a comparable threshold.
The criteria exist. Almost nobody connects them to anything.
The list above is not secret. It sits on public health pages, written in the language of gynecology, usually under a heading about managing symptoms. What is almost never said next is the part that matters to this Foundation.
Heavy bleeding and bleeding between periods are the same signal that endometrial cancer produces. About nine in ten endometrial cancers are found because a woman bleeds and reports it. Most heavy bleeding is not cancer. Some of it is, and there is no way to tell from the outside which is which.
So the rule is not there to frighten you. It is there so that the sentence “my periods have always been heavy” stops being a reason to wait, and starts being a reason to have it looked at once, properly.
The thing years of heavy periods do to you
If your periods have been heavy since you were nineteen, you have no baseline to compare against. The change that matters is not heaviness. It is a change in heaviness, and after fifteen years you have stopped measuring.
This is the trap the research keeps finding. Women with a long history of heavy bleeding are slower to report a change, because the change does not feel like a change. It feels like a bad month in a long run of bad months.
The comparison that matters is you six months ago, not the woman next to you.
Fibroids explain heavy bleeding. They do not rule anything out.
Fibroids are common, benign, and a genuine cause of heavy periods. Having them is a real answer to the question of why you bleed the way you do.
They also create two problems that are worth knowing about. The first is that once fibroids are on your chart, new bleeding tends to get attributed to them, which can close a conversation early. The second is physical: fibroids make the lining of the uterus harder to see on an ultrasound, so the test that would normally reassure you is working against a handicap.
What that means for the scan
In a simulated cohort, ultrasound triage at the common 4 mm threshold had 47.5 percent sensitivity in Black women compared with 87.9 percent in white women, and fibroids are part of why. This gap was identified and named by Dr. Kemi Doll, whose work with ECANA put it in front of the field.
In April 2026 ACOG updated its guidance to recommend both ultrasound and endometrial tissue sampling at the initial evaluation for most women with postmenopausal bleeding. If a scan is the only thing on offer and your bleeding has changed, asking about tissue sampling is a reasonable question.
Doll et al., JAMA Oncology, 2021. ACOG, Obstetrics & Gynecology, April 2026.What to track, and for how long.
You do not need an app or a spreadsheet. You need four numbers from one period, written somewhere you will still have them in a month.
Day one and last day.
Two dates. This gives you length, which is the seven day test, and it is the first thing you will be asked.
Your heaviest day, in changes.
How many pads or tampons, and roughly how many hours each one lasted. “Six in a day, about ninety minutes each” is a clinical fact. “Very heavy” is not.
Clots bigger than a quarter, yes or no.
And roughly how many. You will not remember this later. Write it down in the moment.
Anything outside the period itself.
Spotting between periods, bleeding after sex, or discharge that is new for you. This is the item most likely to change what happens at the appointment.
“My periods have changed. Here is what I tracked for one cycle. I would like it evaluated, and I want to know whether I need tissue sampling and not only a scan.”
Most heavy bleeding has an ordinary explanation. Fibroids, hormonal changes, perimenopause, polyps, a coil, thyroid trouble. The great majority of women who get this looked at will be told something reassuring, and that is the likeliest outcome for you.
The reason to go anyway is that the small fraction where it is something else is almost entirely made up of women who had this exact signal, early, and were told by themselves or by someone else that it was probably nothing. Getting it checked once is how you leave that group.
This page is health information, not medical advice, and it cannot tell you what is happening in your body. Someone who examines you can.
Send this to one woman you know.
Almost every woman who goes early says the reason was another woman telling her to. If you have ever had the conversation that starts “is that normal?”, this is the page you wanted then.
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