The sudden dizziness in pregnancy may be caused by anemia. You need to go to the hospital for routine blood tests to see if the hemoglobin is normal. If the hemoglobin is really low, you can take oral blood granules and ferrous sulfate oral solution, and you should usually eat more fish, meat, eggs, milk, chicken liver, shrimp, spinach, etc. Another condition may also be a sudden change in blood pressure during pregnancy, which occurs as an increase or decrease in blood pressure, dizziness and headache caused by gestational hypertension syndrome. You should visit the obstetrics and gynecology department of a regular hospital, measure your blood pressure, and take oral antihypertensive drugs if necessary to avoid damage to the fetus and the pregnant woman. Usually you should drink more water, pay attention to rest, ensure sleep, eat more fresh vegetables and fruits, avoid spicy and stimulating food, and insist on exercising to improve your physical fitness.