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What turns period blood black?

Posted on October 29, 2023

When you menstruate, your blood could come in a range of colors, from deep red and pink to brown and more. However, if you see period blood that's black, you may start to worry. But should this color change be a cause for concern? Here's what you need to know.

What turns period blood black? a black square

Now, before you worry about the color of your flow, let's talk about volume. When you have very heavy periods, or your flow suddenly becomes much heavier, that could be a sign of uterine fibroids. However, during the cycle of any period, color changes are normal, with brown or black period blood showing up more typically at the start or end of your cycle.

Why is that the case? When blood stays in your uterine lining or vagina for a long time, it can oxidize. And that can lead to a darkening in color. As a result, at the start of your cycle, when your uterine lining has been thickening all month, the color may be darker. And the same can be true at the end of your flow, as the last bits of lining are finally shed.

What Else it Could Mean

According to the Cleveland Clinic, most women don't need to worry when period blood turns black. Still, as with any changes to your cycle, it's important to discuss any sudden differences with your doctor. And that's especially true if the color of your flow changes while your period is irregular, or while you've noticed other changes, like passing large clots.

So, what could it mean if your period blood is black? When it comes with heavy flow, you may need to start worrying about anemia, especially if your cycle also lasts longer than 7 days. Now, some women think black period blood is a sign of pregnancy. And, while that's not usually the case, it could be a sign of a miscarriage or ectopic pregnancy. (Since fibroids during pregnancy can increase your risk for miscarriage, this is a critical symptom to mention to your OBGYN.)

Is period blood that's black normal?

This change in your flow color or discharge could be normal. However, it could be a sign of a problem if you also experience irregular periods; could be pregnant; or also notice a foul odor to your discharge. As such, if you notice this color change once or twice, on its own, you probably don't need to worry. However, if your period lasts longer than a week; your cycle is irregular; or you notice other cycle changes, it's time to talk to your doctor.



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