What causes the functional closure of the ductus arteriosus in a full-term infant?

The functional closure of the ductus arteriosus in a full-term infant is primarily driven by the changes in pressure within the circulatory system, specifically the decrease in pressure in the pulmonary vasculature coupled with an increase in pressure in the aorta. After birth, the infant's lungs expand, leading to reduced resistance in the pulmonary circulation. This decrease allows for more blood to flow through the lungs, decreasing the pressure in the pulmonary arteries. Simultaneously, the systemic vascular resistance increases as the newborn begins to rely on their own circulatory system to deliver blood throughout the body.

The combination of these pressure changes leads to the functional closure of the ductus arteriosus, which is crucial in redirecting blood flow away from the pulmonary artery towards the lungs for oxygenation. This transition is essential for the newborn, ensuring proper oxygen supply and establishing an effective cardiovascular system outside the womb.

While increased oxygen levels in the blood can play a role in the long-term structural closure of the ductus arteriosus, it is the immediate changes in pressure that are primarily responsible for its functional closure at birth. Additionally, while the closure of the foramen ovale is an important aspect of neonatal circulation changes, it does not directly influence the functional