The black menstruation but pregnant, this phenomenon appears there are two possibilities: 1, radical menstruation, in pregnancy after the menstruation can still come on a monthly basis, only the amount is relatively small, the time is relatively short, the pregnant woman and the fetus are not obvious damage, belong to a kind of physiological phenomenon. 2, there may be after the pregnancy after the symptoms of a priori miscarriage, if this is the case you need to be actively preservation of the fetus. If you have a dark period, but you find out that you are pregnant, it is recommended that you test your progesterone, and if it is low, you will need to be treated with fertility preservation. If the progesterone is not low and there is no discomfort, you can observe for the time being, and indeed there is a surge of menstruation medically also known as bloom, usually with the growth of the fetus, the blood will stop naturally.