What causes the blood to be black at the beginning of my menstrual cycle?

Answer by  ladydoc (22)

The black or brownish fluid at the beginning of the menstrual cycle is often residue or old blood from the last menstrual cycle. As the uterine lining sheds, you may notice black and reddish clots. If the menstrual fluid does not have a pink or red color within a day or two, see your doctor.

Answer by  CJOVAN (80)

The black (most likely dark-brown) menstrual fluid is often "old" build up that was not expelled during the previous menstrual cycle. There is generally no cause for concern unless the fluid does not begin to take a red/pink color within 1-2 days.

Answer by  kcastle (2)

and the same thing happend last month and my cycle was light and for only like 3 days.