Serial changes in renal haemodynamics during normal human pregnancy.

Effective renal plasma flow (ERPF) and glomerular filtration rate (GFR) were determined at constant intervals during and after the normal pregnancies in 25 healthy women. Compared with non-pregnant values, ERPF increased by 80 percent during early pregnancy but fell significantly from this new level during the third trimester. GFR, however, remained at a level 50 per cent above the non-pregnant throughout pregnancy. Filtration fraction (GFR/ERPF) was significantly reduced during early pregnancy but rose to a value equivalent to the non-pregnant during the third trimester. Comparable data of previous workers are re-interpreted.