Period blood A–Z

Period blood A–Z

We need to talk more about period blood. Yup, we said it. Although it is something we deal with regularly, it still feels like something that needs to be kept quiet and endured with stoicism each month. Let's face it, the absence of knowledge is not helpful and can undoubtedly leave you worrying about your period and yes, we have all been there. As Dr. Jen Gunter, renowned Gynecologist states, “no one ever benefited by learning less about their body” [1]. Your period blood has a story to tell and can reveal a lot about your overall health. So much so that the American College of Obstetricians and Gynaecologists even considers menstruation a vital sign [2]! We're here to help you understand it.

What is period blood?

Period blood is blood…right? Well, kind of. Period blood is actually only composed of around 30-50% blood [3]. The rest is endometrial cells and secretions from the vagina and cervix [4]. If you are surprised, know that you're not the only one who didn't learn this information in health class.

Myth busting corner:

Myth: Period blood is dirty

Truth: There is still a large portion of society that considers periods dirty, impure, and even toxic [5, 6]. But the truth is that there is nothing dirty about them! Periods are a normal and healthy bodily process, and they are no more unsanitary than other forms of blood or bodily fluids. So, let’s drop the shame.

What should my period blood smell like?

I’m guessing that this question has arisen for most of us, at one point or another. What should it smell like? Well, everyone who menstruates will have a unique natural scent to their period blood. This is attributed to the bacteria in your vagina, known as the vaginal flora, and a dash of copper [7]. However, if you do notice any unusually strong or unpleasant smells during your period, it’s best to speak with your healthcare provider.

Period blood consistency

Period blood consistency and texture can vary for everyone. Whether it is thick, thin, clumpy, jelly-like or sticky, these are typically all variations of normal.

Blood clots in period

  • Some people may pass clots with their period.
  • Clots are formed when menstrual blood gets shed from the lining and clots in the uterus.
  • The body needs time to make anticoagulants to break down clots and re-liquify the blood.
  • On days when the period is heavier and blood flow is fast, the body has less time to break down clots, which might pass through the vagina.
  • Most of the time, passing clots is not a cause for concern.
  • Keep an eye out for large clots (greater than a quarter or over 2.5cm) as this can be a sign of heavy periods, also called menorrhagia.

What is a watery period?

Some months, your period blood may be more thick and clotted in appearance, while other times, it may be more thin and watery. This is generally normal, what is important is to be aware of any changes in your period blood consistency, or if it stops altogether and you aren’t sure why, and to not be afraid to consult a healthcare provider if you notice anything unusual.

Period blood colours

Period blood can come in a variety of colours, the most common being red and brown, but it can also be pink, dark brown, or even black. Want to learn more? Check out our article on period blood colours.

How much period blood leaves the body?

The amount of blood loss during a menstrual period can vary from person to person. For some, it is as little as 10 ml and for others, as great as 80mls. The average person loses between 30ml and 40ml, which is about 2 to 3 tablespoons [10]. If you compare that to the amount of blood you would lose at a blood donation, which is 470 mls, it’s not actually very much!

What is a heavy period?

A heavy period is defined as a loss of greater than 80 mls during menstruation. In simpler terms, this could be classified as needing to change pads, tampons or period underwear every hour for several hours in a row, bleeding for longer than 7 days or any excessive menstrual blood loss that affects your quality of life. If you are concerned that you might be experiencing this, talk to your healthcare provider. You can read more about heavy periods here.

Embracing your period

From menarche (your first period) to menopause (your last period), menstruation occurs in hundreds of millions of girls, women, transgender men, and non-binary persons each day. As you may have guessed by now, paying attention to your period can reveal a lot about your overall health. Of course, there is so much beautiful variation when it comes to period blood colours, consistency, texture, and heaviness but what is important is knowing what is normal for you. We recommend tracking your cycle (there are plenty of cycle tracking apps available or a good ol diary does the job just fine) to prompt if anything seems unusual or unfamiliar. After all, we can barely remember what we had for breakfast - let alone the details of a period months before. If you feel concerned or if something doesn’t seem right, always speak with your healthcare provider.

  • 1. Gunter J. The Vagina Bible: The Vulva and the Vagina -- Separating the Myth from the Medicine: Citadel Press; 2019.
  • 2. Care ACoAH. ACOG Committee Opinion No. 349, November 2006: Menstruation in girls and adolescents: using the menstrual cycle as a vital sign. Obstet Gynecol. 2006;108(5):1323-8.
  • 3. Fraser IS, McCarron G, Markham R, Resta T. Blood and total fluid content of menstrual discharge. Obstet Gynecol. 1985;65(2):194-8.
  • 4. Yang H, Zhou B, Prinz M, Siegel D. Proteomic analysis of menstrual blood. Mol Cell Proteomics. 2012;11(10):1024-35.
  • 5. Garg S, Anand T. Menstruation related myths in India: strategies for combating it. J Family Med Prim Care. 2015;4(2):184-6.
  • 6. Johnston-Robledo I, Chrisler JC. The Menstrual Mark: Menstruation as Social Stigma. Sex Roles. 2013;68(1):9-18.
  • 7. Jones MM. Human Reproductive Biology: Elsevier Science; 2012.
  • 8. Dasharathy SS, Mumford SL, Pollack AZ, Perkins NJ, Mattison DR, Wactawski-Wende J, et al. Menstrual bleeding patterns among regularly menstruating women. American journal of epidemiology. 2012;175(6):536-45.
  • 9. Garry R, Hart R, Karthigasu KA, Burke C. A re-appraisal of the morphological changes within the endometrium during menstruation: a hysteroscopic, histological and scanning electron microscopic study. Hum Reprod. 2009;24(6):1393-401.
  • 10. Fraser IS, Critchley HO, Broder M, Munro MG. The FIGO recommendations on terminologies and definitions for normal and abnormal uterine bleeding. Semin Reprod Med. 2011;29(5):383-90.
  • 11. Sriprasert I, Pakrashi T, Kimble T, Archer DF. Heavy menstrual bleeding diagnosis and medical management. Contracept Reprod Med. 2017;2:20.

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