Normally, the placenta is attached to the anterior, posterior or lateral wall of the upper uterine body, but if it is attached to the lower uterine segment or the inner uterine orifice, it is considered placenta praevia. The most typical symptom of placenta praevia is painless and recurrent vaginal bleeding in late pregnancy. What is placenta praevia? Normally, the placenta is attached to the anterior, posterior or lateral wall of the upper uterine body, but if it is attached to the lower uterine segment or the endometrium, it is considered placenta praevia. Placenta praevia usually occurs because the endometrium is not sound, too many births or miscarriages, excessive scraping that damages the endometrium and infects it; or in twin births, the placenta is large and extends downward because it needs more blood supply; or the fertilized egg is delayed in development and lacks the ability to grow when it reaches the bottom of the uterine cavity and continues to move down to the lower part of the uterus, implanting in the uterine wall and forming placenta praevia. What are the risks of placenta praevia? The most typical symptom of placenta praevia is painless and recurrent vaginal bleeding in late pregnancy. The bleeding often occurs unknowingly, and sometimes the pregnant woman wakes up only to find herself in a pool of blood. Some women bleed only once, while others bleed repeatedly and more often than not. Small amount of repeated bleeding can easily lead to anemia, while large amount of bleeding can lead to shock, which can endanger the life of mother and baby if not treated in time. The main effects of placenta praevia on the mother are postpartum bleeding and infection. Because the placenta is attached to the lower part of the uterus, the tissue is thin and brittle, which can easily lead to tearing and bleeding during delivery, and the contraction of the lower part of the uterus is weak, so the placenta is not easy to be completely detached after delivery, which can cause postpartum hemorrhage, and with repeated bleeding, pregnant women are often combined with anemia, so their resistance is low and they are prone to postpartum infection. The anterior placenta also has a greater impact on the fetal baby. Repeated bleeding of the placenta anterior can easily cause preterm delivery; premature abruption and pressure of the placenta anterior can make the placenta ischemic and hypoxic, which can easily cause intrauterine asphyxia of the fetus; because the placenta occupies the lower part of the uterus, it prevents the fetal head from entering the entrance of the maternal pelvis, resulting in abnormal fetal position such as breech position and transverse position with higher incidence than normal. Preterm labor and hypoxia are common causes of fetal infant death. Therefore, regardless of the amount of vaginal bleeding in late pregnancy, you should be sent to the hospital for a clear diagnosis and receive early treatment to avoid delaying the condition and endangering the life of the mother and baby.