Dizziness

Any one else have low blood pressure before pregnancy? I have extremely low blood pressure normally.. like 114/56 is my normal but causes dizzy spells. This is my fifth baby and because my blood pressure is low when the veins and arteries widen to allow more blood flow my blood pressure drops more making me feel like im gonna pass out... I have to greatly increase my salt.. crave it actually.. Anyone else have a problem with severe dizziness??