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the most important thing to know about the color of menstrual blood
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changes in the color of menstrual blood are normal
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Dark red, brown, or black menstrual blood is simply blood that has reacted with oxygen
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Talk to your healthcare provider if you have grayish or pinkish watery discharge, as this may be a sign of an infection or something more serious like cancer.
You may notice that the color of your period blood varies. sometimes it’s a little brown, or almost black, then turns bright crimson.
Underlying health conditions are more likely to affect the timing and length of your period than its appearance, but there are a few reasons why your period blood may vary in color.
what does the color of your menstrual blood mean?
Blood (and tissue) changes color depending on how long it has been exposed to oxygenated air. think of when you cut your skin: red blood comes out of a fresh wound. if you put a bandage on it and check it the next day, you will see that the blood that was once red will have turned brown. most of the water in the blood will have evaporated, producing a more concentrated pigmentation.
Your endometrium is the inner lining of your uterus, which is where a fertilized egg would implant and grow. the endometrium is made up of highly vascularized tissue with special spiral arteries (1). this provides a fertilized egg with quick and easy access to a fresh blood supply (which carries nutrients and oxygen), so it can begin to develop.
Just before your period comes, these specialized spiral arteries constrict to limit blood loss (1, 2). after constriction of the spiral arteries, the endometrium begins to shed in pieces from the deeper layers of the uterus (3). your endometrium does not separate all at once, it is a slower and more controlled separation, and it takes a while for the endometrial tissue to descend through the cervix and vagina. this early blood and tissue may appear dark red or brown, or even black because they take longer to leave the body.
As the tissue breaks away, it leaves torn ends of blood vessels that continue to bleed (3, 4). this is where the bright red blood you may see during your period comes from. eventually, platelets (pieces of cells involved in blood clotting) are activated to clump together and form a plug to stop bleeding, ending the period (2).
As the bleeding subsides towards the end of a period, it may return to a dark red or brown color.
what does black, brown or dark red menstrual blood mean?
At the beginning or end of your period, your blood may be dark brown or red in color and may have a thick consistency, but it’s also normal for the first signs of your period to be bright red and more fluid.
If you notice brown menstrual blood at the beginning or end of your period, it’s because the blood is older and took longer to leave the uterus. the uterine lining darkens the longer it takes to leave the body.
menstrual blood clots are normal on the heaviest days of your period and may also appear dark red or almost dark black.
what does it mean if my period blood is bright red?
Period flow usually becomes heavier on the second or third day of the cycle as the uterine lining sheds faster. Bright red menstrual blood is newer blood, so it doesn’t have time to darken before it leaves your body.
what does it mean if my period blood is pink?
Spotting is any bleeding that occurs outside of your regular period. some people experience mid-cycle spotting, also known as ovulation bleeding (4, 5). bleeding that mixes with fertile cervical fluid may appear light red or pink.
Pink, watery vaginal discharge that occurs irregularly (without a pattern and not related to your menstrual cycle) may be a sign of cervical cancer and should be evaluated by a health care provider (6).
what does it mean if my period blood is grey?
If you have grayish discharge, this could be a sign of infection. If you experience heavy bleeding with chunks of grayish tissue, this could be a sign of miscarriage. Seeing a health care provider is recommended for any situation.
the importance of menstrual blood color is often misunderstood
Reproductive and menstrual health is still seriously misunderstood and pushed aside compared to other aspects of health. The lack of adequate education and research on aspects of women’s health negatively affects people around the world in many ways. On track, we are committed to improving research on menstrual and reproductive health.
a range of menstrual blood colors is typical and does not mean anything serious
Changes in the color of your period blood are often nothing to worry about. But pay attention to your flow volume, changes in cycle length, pain, or any bleeding that doesn’t have a pattern, as these may indicate underlying conditions.
The article was originally published on October 1. 19, 2017.
