The pathogenesis of the occurrence of placental abruption is unclear and may be related to vascular pathology, mechanical factors, and sudden decrease in intrauterine pressure. Placental abruption is a serious complication in late pregnancy, which develops rapidly and requires timely management. 1. Vascular lesions: most often seen in pregnant women with eclampsia, chronic kidney disease, chronic hypertension, systemic vascular lesions. The disease causes capillary degeneration and necrosis or even rupture and bleeding, and the blood forms a hematoma between the uterus and the placenta, leading to separation of the placenta from the uterine wall. 2. Mechanical factors: Placental abruption is induced by trauma to the abdomen of pregnant women, impact, external inversion, etc. 3. Sudden decrease in intrauterine pressure: usually occurs in premature rupture of membranes at term, excessive amniotic fluid, twin pregnancy delivery, when the first child is delivered too quickly, when the uterus suddenly contracts. The pathogenesis of placenta previa is not clear, once a pregnant woman suffers from placenta previa, she must be treated in a timely manner. Delay in treatment will not only jeopardize the fetus, but also put the life of the pregnant woman at risk.