Effect of changes in body posture on vasoactive hormones in pre-eclamptic women.

The aim of this study was to determine the normality or otherwise of neurohormone indices, particularly the sympathetic nervous system, in pre-eclamptic patients and document whether changes in body posture magnify any differences between pre-eclamptic and normal women. We studied 11 women with pre-eclampsia and compared them with 17 matched normotensive pregnant women and eight nonpregnant women. Measurements of arterial pressure, heart rate and neurohormones were carried out with subjects in the left lateral position, then supine, left lateral, with upright posture and finally with assumption of the left lateral position again. Main outcome measures were arterial pressure, heart rate and hormones (plasma norepinephrine, renin activity, natriuretic peptides and endothelin-1). We observed that plasma norepinephrine levels were higher in pre-eclamptic than normotensive pregnant women and this was most obvious in the upright position. Plasma renin activity was likewise higher in pre-eclamptic than normotensive pregnant women, again most obvious with upright posture. Plasma natriuretic peptides and endothelin-1 levels were similar in pre-eclamptics and normotensive pregnant women. These data strengthen the premise that pre-eclampsia is associated with sympathetic overactivity as reflected by plasma norepinephrine levels, most obviously observed in the upright position.