AN ORTHOSTATIC UTEROVASCULAR SYNDROME - A PROSPECTIVE, LONGITUDINAL-STUDY

OBJECTIVE: The interaction between maternal hemodynamics and uterine activity in the upright position was investigated longitudinally (358 measurements) in 40 healthy pregnant women from 20 gestational weeks to term. STUDY DESIGN: Maternal-fetal hemodynamic parameters and uterine contractions were measured noninvasively in four different postures. RESULTS: Hemodynamic disturbances caused by compression of pelvic vessels by the gravid uterus in the upright position were detected in two of 40 (5%) women as early as 24 weeks' gestation; a peak was reached at 38 weeks (71%). With a decrease in the stroke volume (22%, p < 0.001) neither the cardiac output (- 11%, p < 0.05) nor the systolic blood pressure (- 1.4%, p < 0.05) remained constant, although there was a compensatory heart rate increase. CONCLUSION: A significantly increased number of spontaneous uterine contractions in the upright position is associated with release of the blocked venous return flow and restoration of normal maternal hemodynamics.