Neonatal circulation refers to the blood flow system in newborns, which is significantly different from that in older children and adults. At birth, the placenta is no longer used for oxygen and nutrient exchange, leading to changes in how blood circulates. The ductus arteriosus and foramen ovale are two key structures that close shortly after birth, allowing blood to flow directly to the lungs for oxygenation. In a newborn, the heart pumps oxygen-rich blood from the lungs to the body, while oxygen-poor blood returns to the heart. This transition is crucial for the newborn's survival, as it establishes a functional pulmonary circulation that supports breathing outside the womb.