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Circulatory adaptation to pregnancy--serial studies of haemodynamics, blood volume, renin and aldosterone in the baboon (Papio hamadryas).

Authors
Type
Published Article
Journal
Journal of Hypertension
0263-6352
Publisher
Ovid Technologies (Wolters Kluwer) - Lippincott Williams & Wilkins
Publication Date
Volume
4
Issue
6
Pages
773–779
Identifiers
PMID: 3546496
Source
Medline
License
Unknown

Abstract

To test the hypothesis that haemodynamic changes in pregnancy precede any significant increase in circulating blood volume, serial haemodynamic studies were performed in eight baboon pregnancies using Swan-Ganz catheterization and arterial cannulation. Simultaneous measurements were made of red cell and plasma volumes, and of plasma renin activity and aldosterone concentration. Haemodynamic changes identified by 4 weeks gestation included significant (P less than 0.01) reductions in right atrial pressure, systemic and pulmonary arterial pressures, and systemic and pulmonary vascular resistance. Stroke volume increased in early pregnancy (P less than 0.01), with a consequent increase in cardiac output. Plasma renin activity and aldosterone concentration were elevated by 4 weeks (P less than 0.01), but plasma volume did not expand until 12 weeks. At no stage in middle or late pregnancy was cardiac filling pressure increased. These results provide the first haemodynamic evidence that pregnancy is a state of reduced effective blood volume associated with vasodilatation from the early weeks.

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