title: Decreased intervillous and unchanged myometrial blood flow in supine recumbency.
abstract: The supine position in late pregnancy is associated with many hemodynamic changes caused by compression of the inferior vena cava and a resulting fall in cardiac output. To investigate the effect of this position on uteroplacental blood flow, 22 women with normal (N = 12) or hypertensive (N = 10) pregnancy were investigated using the intravenous 133Xe washout method, in both the supine and left-tilted (45-degree) lateral positions. The intervillous blood flow (113 +/- 48 ml/min/dl) was lower in the supine position than in the left-tilted position (141 +/- 48 ml/min/dl) (P less than 0.01), while the myometrial blood flow was similar in both (9.0 +/- 3.3 ml/min/100 g in supine and 8.7 +/- 2.7 ml/min/100 g in left-tilted position). The results suggest that the autoregulation system for uteroplacental circulation is operative only in the nonplacental component of the pregnant uterus.
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D010477:Perfusion; D010920:Placenta / Q000098:blood supply*; D011187:Posture; D011247:Pregnancy; D012039:Regional Blood Flow; D014599:Uterus / Q000098:blood supply*