Objective: Early pregnancy is characterized by a fall in total peripheral vascular resistance. In this study we tested the hypothesis that this phenomenon is accompanied by rising compliances of the large arteries and veins.
Study design: In 42 women with a history of preeclampsia and 10 healthy parous control subjects we measured the following variables in the midfollicular phase and the midluteal phase during the menstrual cycle and again at 5 and at 7 weeks of amenorrhea: cardiac output, mean arterial pressure, carotid and femoral artery compliances, and venous compliance. The total peripheral vascular resistance was determined as the ratio of mean arterial pressure and cardiac output. After screening for thrombophilia and hypertension, women with a history of preeclampsia were divided into subgroups with hypertension, thrombophilic disorders, and no underlying abnormalities.
Results: In parallel with the fall in total peripheral vascular resistance during early pregnancy, femoral artery compliance and venous compliance increased in the control group. Except for venous compliance, these changes were also observed in the women with thrombophilia and a history of preeclampsia. In the subgroups of the women with a history of preeclampsia with hypertension and with no underlying disorder both arterial and venous compliance failed to increase despite a drop in total peripheral vascular resistance.
Conclusion: These data support the concept that during normal pregnancy the fall in total peripheral vascular resistance is paralleled by improved macrovascular compliance. The latter adaptive change did not occur in women with a history of preeclampsia with hypertension or without an underlying disorder.