Fetal Blood Flow
Before birth, the fetus needs a reduced blood flow to the lungs (since they aren�t functioning). So blood must be diverted from the right side to the left side of the heart. This is accomplished with two �shunts:� the foramen ovale and ductus arteriosus. The foramen ovale shunts blood from the right atrium into the left atrium. The ductus arteriosus shunts blood from the pulmonary trunk into the aorta. Since the blood coming to the fetus does not need to be detoxified by the liver, there is also a shunt (the ductus venosus) which allows blood to bypass the liver.