Menstruation is the means by which the uterine lining is expelled from the body each month. During the three to seven days it takes for most women to complete a menstrual cycle, changes in blood color may be noted. It is important to keep track of your cycles to best understand what your menstrual blood color means. 

Bright Red BloodBrown and Red
Typically, the first couple days of your menstrual period will show as bright red blood. This is new blood just shed from the uterus. The blood tends to be thinner and flows more freely. 

Dark Red Blood – Thicker
As your menstrual period nears mid-week, you may notice a slower flow and darker color. This is because the majority of the uterine lining has shed and older blood is mixing with newer blood. As older blood sits in the uterus, it grows darker and thicker. 

Dark Brown Blood
By the end of your menstrual period, the body is flushing leftover blood and uterine lining out of the body. Older blood tends to be a darker red or brown color. Some women even report blood that looks black. Clots may also be present. 

Brown Blood From the Start
There are times when you’ll notice brown blood from the start of your menstrual period. Some doctors suggest this is just old blood making its way out of the body during the days prior to your actual menstrual period. If there is burning, itching or irregular odor associated with the brown blood there could be an infection. 

Your menstrual period is the time when the uterine lining sheds in preparation of the next fertility cycle. Not all blood looks the same and the longer you have your period, the more apt you are to notice changes in color. The first true days of menstrual flow should be bright red with the color gradually growing darker as your cycle nears its end.