The causes of low blood pressure in pregnant women are as follows: 1. Lean body mass: common in frail, light weight people, body mass index <18, can cause low blood pressure in pregnant women. Improvements can be made through a balanced diet, meat and vegetables, and more intake of foods rich in iron, folic acid and vitamins. After pregnancy, pay attention to consume more meat food, animal liver, egg yolk, etc., and gradually increase weight, which can improve the low blood pressure. 2, anemia: anemia before pregnancy can lead to low blood pressure, such as Guangdong, Guangxi, Hunan and other two regions, the incidence of thalassemia is more likely, belongs to the congenital genetic genetic disease, manifested as headache, dizziness, low blood pressure. The 12-week maternity screening can be clarified, and it is recommended to improve anemia and low blood pressure by supplementing with drugs if anemia is clearly present.