Question

what could be the cause of black blood during periods . ​

Answer 1

Answer:

the reason is that ruptured endometryum

Explanation:

hope it will help you

Answer 2

Answer:

Your menstrual flow may be slower at the beginning and end of your period. As a result, the blood in your uterus may take longer to exit your body and change from the standard red to a dark brown or black. If you see black spotting before your period, it may also be blood left over from your last period.