How quickly does a PDA close?

How Quickly Does a PDA Close After Birth?

Shortly after a baby takes its first breath, remarkable changes begin in the circulatory system. One of the most critical is the closure of the patent ductus arteriosus (PDA)—a blood vessel that connects the pulmonary artery to the aorta and is essential in fetal circulation. In most healthy newborns, this ductus begins closing within the first 12 to 24 hours after birth.

This rapid functional closure is triggered by increased oxygen levels in the blood once breathing starts. The smooth muscle in the walls of the ductus responds to higher oxygen tension, along with shifts in certain biochemical factors like acetylcholine, bradykinin, and endothelin. These signals prompt the vessel to constrict, effectively shutting off the abnormal flow between the aorta and pulmonary artery.

While the duct usually stops carrying blood within the first day, complete anatomic closure—where the vessel fully seals and turns into fibrous tissue—can take several weeks. In some cases, especially in premature infants, the PDA may remain open longer, requiring medical intervention. But for full-term babies, this transition is a natural and efficient process, marking a key milestone in adapting to life outside the womb.

Understanding the timing and mechanism of PDA closure helps clinicians monitor newborns, especially those at risk for persistent ductal patency. Fortunately, in most cases, the body handles this transition seamlessly, often without anyone even noticing.