In the case of a normal delivery, most of the bloody discharge will be cleared within 9 days. After a cesarean section, the bloody discharge will last a little longer, but most of them will not last more than half a month. If there is still blood in the vagina after 40 days of giving birth, it is an abnormal phenomenon, which is often caused by the following reasons:1. Residual placental tissue or fetal membranes in the uterine cavity, which will cause bloody discharge, often accompanied by pain in the lower abdomen.2. Infections, caused by infections in the uterine cavity, which will also result in bloody discharge, which may be accompanied by smelly discharge or pain in the lower abdomen, or even fever. 3. Postpartum fever. 3, because the postpartum has been taking ginseng, deer antler or taking stew made with wine, can also lead to prolonged bloody discharge, so in addition to the examination, but also recall their own daily life in the diet, to give attention.