What happens to the ductus arteriosus after the baby's first breath?

After a baby's first breath, the ductus arteriosus, which is a fetal blood vessel connecting the pulmonary artery to the aorta, undergoes a significant physiological change. This vessel is crucial during fetal life because it allows blood to bypass the lungs, which are not used for gas exchange before birth. However, upon the infant's first breath, several changes occur in the circulatory system.

When the baby takes its first breath, oxygen levels in the blood increase, leading to the expansion of the pulmonary blood vessels and a reduction in pulmonary vascular resistance. As a result, blood flow through the lungs increases, and the pressures in the left atrium rise above those in the right atrium. This new pressure dynamic closes the ductus arteriosus, typically within the first hours to days after birth. Over time, the ductus arteriosus is transformed into a fibrous remnant known as the ligamentum arteriosum.

This process is a normal part of transitioning from fetal to postnatal circulation, enabling the baby to effectively utilize its lungs for oxygenation. This closure generally signifies that the baby is adapting well to life outside the womb. Options that suggest the ductus arteriosus expands, remains open for several months, or revers