A blood pressure of 120/80mmHg or less is considered normal. High blood pressure means systolic blood pressure should not be higher than 140mmHg, and low blood pressure means diastolic blood pressure should not be higher than 90mmHg. There are many reasons for elevated blood pressure, the most common one is caused by pregnancy, and it is also affected by hereditary factors, liver and kidney diseases. When a pregnant woman has elevated blood pressure, she should be actively treated with antihypertensive treatment to keep her blood pressure stable, because high blood pressure will limit the growth and development of the fetus and will lead to an increase in the resistance to blood flow in the umbilical artery, which may lead to intrauterine foetal death at any time. If the diastolic blood pressure exceeds 140 or 90 mmHg, it means that the patient has high blood pressure, and this kind of situation needs to be treated with antihypertensive drugs as prescribed by the doctor.