What is the advantage of the circuit of fetal blood flow through the ductus arteriosus?

The benefit of the circuit of fetal blood course through the ductus arteriosus is the ductus arteriosus will permit more blood to go to the placenta and sidestep the lungs (since there is no blood required there yet). I hope the answer will help you. 

Stand or kneel behind the child and wrap your arms around his or her waist. locate the navel with one or two fingers in the middle of the child’s abdomen. just above the navel and well below the lower tip of the breastbone