Venous reactivity and pregnancy abnormalities.

An impedance plethysmograph recording was obtained on at least two occasions from 162 women between their 24 and 36th week of pregnancy; 29 while in labor and 21 at the time of their 6-week postpartum visit. There was a significant increase in venous capacitance and a decline in venous capacitance index during apparently normal pregnancy. Those with pregnancy complications (hypertension, premature labor and fetal growth retardation) appeared to have significantly abnormal venous reactivity. It is proposed that equal consideration be given to abnormal venous activity in the mechanisms and therapy of pregnancy-related cardiovascular abnormalities.