Neonatal (Fetal) circulation is the blood flow system before birth that supplies oxygen and nutrients to the fetus from the placenta (not the lungs).

Key Features

• Lungs are not functional

• Oxygen comes from the placenta

• Blood bypasses lungs & partially bypasses liver

Main Pathway

1. Placenta → Umbilical Vein
   Oxygen-rich blood enters the fetus

2. Ductus Venosus
   Shunts blood past the liver → Inferior Vena Cava

3. Right Atrium

   • Most blood passes through Foramen Ovale → Left Atrium

   • Small amount goes to Right Ventricle

4. Left Atrium → Left Ventricle → Aorta
   Supplies brain & upper body with oxygenated blood

5. Right Ventricle → Pulmonary Artery

   • Blood bypasses lungs via Ductus Arteriosus → Descending Aorta

6. Umbilical Arteries → Placenta
   Deoxygenated blood returns to placenta