All are true about uteroplacental circulation except

A mature placenta has a volume of about 500 ml of blood; 350 ml being occupied in the villi system and 150 ml lying in the intervillous space. Intervillous blood flow at term is around 500 - 600 ml per minute. The blood in the intervilllous space is completely replaced 3-4times. Ref : Dutta book of obstetrics 8th Ed