Effect of labor on maternal cerebral blood flow velocity

Blood vessels in the brains of pregnant women may dilate during delivery to protect the brain from adverse changes in blood pressure. Researchers used an ultrasound probe that can be placed against the head to measure blood flow in the brains of 15 pregnant women during delivery. During labor, blood flow in the brain fell significantly even during contractions and active pushing. This indicates that the blood vessels in the brain dilate, or become bigger.