title: An orthostatic uterovascular syndrome--a prospective, longitudinal study.
abstract: 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.
  
  
  METHODS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Obstetrics, University Hospital, Zurich, Switzerland.
authors.forename: K T
authors.initials: KT
authors.lastname: Schneider
authors.forename: P
authors.initials: P
authors.lastname: Bung
authors.forename: S
authors.initials: S
authors.lastname: Weber
authors.forename: A
authors.initials: A
authors.lastname: Huch
authors.forename: R
authors.initials: R
authors.lastname: Huch
mesh_terms: D000328:Adult; D001794:Blood Pressure; D002302:Cardiac Output; D005260:Female; D006339:Heart Rate; D006439:Hemodynamics; D006801:Humans; D008137:Longitudinal Studies; D010388:Pelvis / Q000098:blood supply; D011187:Posture; D011247:Pregnancy; D011446:Prospective Studies; D013318:Stroke Volume; D013997:Time Factors; D014590:Uterine Contraction; D014599:Uterus / Q000502:physiology*