What vessel carries most oxygenated blood in a newborn?

The vessel that carries most oxygenated blood in a newborn is the umbilical vein. In fetal circulation, the umbilical vein is responsible for transporting oxygen-rich blood from the placenta to the fetus. This blood is enriched with oxygen after being oxygenated in the maternal blood supply, and the umbilical vein brings this vital source of oxygen directly to the fetus's body.

After birth, the umbilical cord is clamped and cut, ending the function of the umbilical vein. Oxygenated blood is primarily then distributed through the aorta to support the newborn's systemic circulation, but initially, during the fetal stage, the umbilical vein is crucial for delivering oxygen to the developing fetus. Understanding this function helps clarify the transition from fetal to neonatal life, as the newborn adapts to breathing air independently.

In contrast, the umbilical artery carries deoxygenated blood from the fetus back to the placenta, and the ductus arteriosus is a vessel that allows blood to bypass the lungs in utero by connecting the pulmonary artery to the aorta. The aorta, while it plays a significant role in systemic circulation after birth, does not carry the most oxygenated blood in a newborn until the transition is complete. Thus