Analysis of maternal circulation and renal function in physiologic pregnancies: Parallel examinations of the changes in the cardiac output and the glomerular filtration rate

Abstract

The increase of GFR and the cardiac output during pregnancy are contributed to volume-establishment and to the cessation of the special "underfilled" condition of the maternal circulation in the normal pregnancy. We suppose that the maximal increase of GFR precedes the maximal increase of the cardiac output because the GFR increase is caused by maximal renal vasodilatation. The increase of cardiac output is caused in the first trimester by the shunt effect of the enhanced renal blood flow of maternal kidneys, and in the second and third trimester by the shunt effect of the feto-placental unit and the shunt effect of the maternal kidneys.