Cerebrovascular response to normal pregnancy: a longitudinal study.

We used a longitudinal study design ( gestational weeks 8, 15, 22, 29, and 36 and 12 wk postpartum) to investigate the effect of normal pregnancy on cerebral autoregulation and pressor response. Blood flow velocities in the right internal carotid artery, end-tidal CO2, and mean arterial pressure (MAP) were simultaneously and continuously recorded in 16 healthy pregnant women during standardized hyperventilation and handgrip. Blood flow velocities were recorded using Doppler ultrasound sampled beat by beat using the ECG signal. The results demonstrate that the vasoconstrictor response to hyperventilation is unchanged during pregnancy. During standardized handgrip, MAP showed a statistically significant increase during pregnancy that did not affect cerebral blood flow. A statistically significant reduction in the MAP response to handgrip was seen in week 36. In conclusion, pregnancy has no impact on cerebral autoregulation. There is an impact on the pressor response resulting in a blunted reaction at week 36, probably caused by a fall in the baroreflex set point.