Blood pressure measurement in pregnant women in the left lateral recumbent position.

To evaluate blood pressure in pregnant women in the left lateral position, we studied indirect blood pressure in 169 patients with normal blood pressure, chronic hypertension, and preeclampsia in the supine and then the lateral recumbent positions. Two additional patients had aortic arch blood pressure compared with indirect measures. For all groups, mean arterial pressure in the lateral position was lower than in the supine position. Regarding direct aortic arch blood pressure, (1) supine blood pressure equaled that in the lateral position and (2) direct blood pressure in the lateral position equaled the mean indirect mean arterial pressure of both arms. Therefore the actual blood pressure in the lateral recumbent position is the combined mean arterial pressure of both arms.