ABSTRACT
Fetal kidneys receive only two to four per cent of cardiac output, compared with 20 per cent in the adult. This low rate of renal blood flow is associated with high renal vascular resistance and a fairly constant glomerular filtration rate (GFR) in the fetus of about 1 mL/min/kg body weight. Fetal GFR is significantly reduced in about 70 per cent of complicated pregnancies. The principal function of the fetal kidneys is to maintain amniotic fluid volume. To this end, the fetus passes about 1000 mL of urine per day at term. Fetal kidneys contribute very little to homeostasis, which is achieved through the action of the maternal kidneys and the placenta, the latter receiving almost 50 per cent of the fetal cardiac output.
