It’s tough to say what a “normal” period is. Every woman produces a unique flow, so everything from a couple days of pantyliners to a week of super-absorbant maxi pads can be considered safe and healthy.
But thanks to science, we do have a few stats on the average period. Per cycle, regularly menstruating women produce an average of 45.5 milliliters of menstrual blood, according to a 2012 study in the American Journal of Epidemiology. The periods lasted an average of five days, with the second day being the heaviest (nope, it’s not just you).
What if your period is *way* heavier than that? Or just heavier than usual? Some variation from month to month is normal, but big changes might hint at a problem. You might have reason for concern if your period has any of the following characteristics, according to the American College of Obstetricians and Gynecologists:
Menstrual bleeding lasts longer than seven days.
You need to change your pad or tampon hourly for multiple consecutive hours.
You need to double up on menstrual products (such as wearing a tampon and heavy pad at the same time).
You have to get up in the middle of the night to change your pad or tampon.
Your periods contain blood clots bigger than a quarter.
If your periods fit one of those descriptions, it may be wise to check in with your ob-gyn. Your heavy flow might actually be trying to tell you something about your health. Here are some of the conditions or factors that may amp up your flow.
Uterine fibroids affect as many as 80 percent of women before the age of 50, according to the U.S. Office on Women’s Health (OWH). These are (usually benign) tumors that develop on the uterine wall, and they can cause pelvic and back pain, pain during sex, frequent urination, and heavy and painful periods.
Copper IUDs, or intrauterine devices, are one of the few types of birth control that are hormone-free, but they tend to cause heavier periods and more severe menstrual cramps—at least at first. Many women find their periods level out and cramps cool down after six months or so. (Find out ways to soothe menstrual cramps here.)
Polycystic ovary syndrome (PCOS) is a hormonal imbalance that causes cysts on the ovaries. Because of abnormally high amounts of androgen hormones, many women with PCOS have irregular or missed periods, but they can also be heavy and painful. Learn more symptoms of polycystic ovary syndrome here.
Endometriosis causes the uterine lining to grow outside of the uterus, and it affects a shocking 11 percent of U.S. women between the ages of 15 and 44, according to OWH. Symptoms of endometriosis include spotting between menstrual periods, having more frequent periods, and experiencing heavy and painful flows.
Certain medications may make menstrual flows heavier. The most common example is aspirin and other blood thinners.
Bleeding disorders can affect your period flow. For example, a condition called hemophilia inhibits the blood’s ability clot, so you may bleed through your pads and tampons—or fill up your menstrual cup—faster.
Thyroid problems upset your hormone regulation, and when the thyroid gland is out of whack, your period usually lets you know. Sometimes your body can make too little (hypothyroidism) or too much (hyperthyroidism) of the thyroid hormone, and your period may lighten up, get heavier, or even disappear altogether. And many things can affect your thyroid hormone regulation, including stress, body weight, excessive exercise, and eating disorders.
Many women suffer silently with troublesome periods for years before getting checked out and learning they have conditions like PCOS or endometriosis. If you’re not sure if you’ve got a “normal” period, don’t be afraid to talk to your doc and seek relief.
Bleeding disorders. Washington, DC: American Society of Hematology. (Accessed on December 31, 2021 at http://www.hematology.org/Patients/Bleeding.aspx.)
Dasharathy SS, Mumford SL, Pollack AZ, Perkins NJ, Mattison DR, Wactawski-Wende J, Schisterman EF. Menstrual bleeding patterns among regularly menstruating women. Am J Epidemiol. 2012 Mar 15;175(6):536-45.
Endometriosis. Bethesda, MD: U.S. Office on Women’s Health. (Accessed on December 31, 2021 at https://www.womenshealth.gov/a-z-topics/endometriosis.)
Heavy menstrual bleeding. Washington, DC: American College of Obstetricians and Gynecologists, 2016. (Accessed on December 31, 2021 at https://www.acog.org/Patients/FAQs/Heavy-Menstrual-Bleeding.)
Menstruation. Washington, DC: U.S. National Library of Medicine. (Accessed on December 31, 2021 at https://medlineplus.gov/menstruation.html.)
PCOS symptoms. Seattle, WA: PCOS Awareness Association. (Accessed on December 31, 2021 at http://www.pcosaa.org/pcos-symptoms.)
Thyroid disease. Bethesda, MD: U.S. Office on Women’s Health. (Accessed on December 31, 2021 at https://www.womenshealth.gov/a-z-topics/thyroid-disease.)
Uterine fibroids. Bethesda, MD: U.S. Office on Women’s Health. (Accessed on December 31, 2021 at https://www.womenshealth.gov/a-z-topics/uterine-fibroids.)
What causes menstrual irregularities? Bethesda, MD: Eunice Kennedy Shriver National Institute of Child Health and Human Development. (Accessed on December 31, 2021 at https://www.nichd.nih.gov/health/topics/menstruation/conditioninfo/causes.)