European journal of obstetrics, gynecology, and reproductive biology
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Eur. J. Obstet. Gynecol. Reprod. Biol. · Dec 1981
The influence of posture upon cardiovascular dynamics throughout pregnancy.
Systemic blood pressure (measured with a zero-randomized sphyngmomanometer), stroke volume and heart-rate (measured with a Minnesota Impedance Cardiograph), hematocrit and their derivatives--cardiac output, pulse pressure, mean arterial blood pressure and peripheral vascular resistance, were assessed in 19 nonpregnant women of child-bearing age and in 27 patients who were examined at regular intervals on 12 to 15 occasions from 8 to 11 wk of pregnancy until 6-wk postpartum. Readings were made with the subjects in each of six positions: supine, reclining, left and right lateral, left and right tilt. The purpose of this paper is to compare the results of these different postures. ⋯ No evidence was found that aortocaval compression led to a change in the measured attributes of central cardiovascular dynamics. For the 'normal unembarrassed parturient' it is suggested that aortocaval compression is rapidly succeeded by a restablization of these attributes to their previous levels, reflecting the prompt establishment of a suitably diminished circulating blood volume within a reduced vascular capacity. It is nevertheless likely that aortocaval compression will interfere markedly with uteroplacental vascular dynamics and hence pose a hazard to the fetus.