Plasma Volume Contraction: A Significant Factor in Both Pregnancy-Associated Hypertension (Pre Eclampsia) and Chronic Hypertension in Pregnancy

The role of plasma volume in hypertension in pregnancy (pre-eclampsla)was investigated. Significant volume expansion from non-pregnantlevels (16·5 ± 1·60 ml/cm height) was presentthroughout pregnancy in 189 normal women, reaching 23·1± 1·21 ml/cm at 33–36 weeks amenorrhoea.In another 40 initially normotensive pregnant women who developedhypertension, simllar early volume expansion was followed bysignificant volume contraction in the third trimester, beforeelevation of blood pressure in 29 (20·6 ± 1·26ml/cm), after it in 11(18·6 ± 1·27 ml/cm).Equivalent volume contraction was present in another 44 womenstudied only after hypertension developed in the third tri mester.Oedema had no value as a clinical sign. In another 30 women with chronic hypertension, blood pressurewas inversely related to plasma volume (r = –0·822)and to fetal growth (r = –0·710), which was directlyrelated to plasma volume (r=0·701). Plasma volume depletionplays a significant role in hypertension in pregnancy.