If a woman is in the ovulation period when the vaginal flow of black blood, the amount of small, and continue for a few days to naturally clean, may be simple ovulation bleeding, once in a while do not need to deal with, this is the hormone fluctuations caused by the stimulation of the performance of the woman’s physical health has no effect, but also will not affect the pregnancy. If a woman is pregnant after the vaginal flow of black blood, most considerations may be the performance of the first sign of miscarriage, is due to a small amount of bleeding in the uterine cavity, the blood in the outflow of the blood after the black blood will be seen, this situation all indicates that the first sign of miscarriage is not serious, and did not continue to develop. This is because women with severe symptoms of preeclampsia have more bleeding and what is seen is mostly bright red blood. If a woman only has black blood on the first day of her period, and there is no significant change in the amount of menstrual flow, this is also a physiological manifestation and can be left untreated and let nature take its course.