Background: Left-lateral tilt position is used to reduce assumed aortocaval compression by the pregnant uterus.
Methods: Magnetic resonance images of 10 singleton parturients at full term and 10 healthy nonpregnant women were obtained for measurement of the abdominal aorta and inferior vena cava volume between the L1-L2 disk and L3-L4 disk levels in both the supine and left-lateral tilt positions (15°, 30°, and 45°) maintained by insertion of a 1.5-m-long polyethylene foam placed under the right side of the parturient's body.