At what age does PDA close?

When Does the PDA Close in Newborns?

Shortly after a baby takes its first breath, a remarkable change happens inside the tiny cardiovascular system. One key transition involves the patent ductus arteriosus, or PDA—a vital blood vessel that was essential in the womb but no longer needed after birth. In most healthy newborns, this ductus begins closing within the first 12 to 24 hours of life.

This closure starts with a functional shut-down, driven by the baby’s exposure to higher oxygen levels outside the uterus. The smooth muscle in the walls of the ductus responds to oxygen, as well as to signaling molecules like acetylcholine, bradykinin, and endothelin, causing it to constrict rapidly. This initial spasm effectively stops blood flow through the vessel and marks the beginning of the transition to independent circulation.

However, just because the ductus stops functioning doesn’t mean it’s gone. The anatomic closure—where the vessel actually transforms into a fibrous ligament—takes longer, often several weeks. During this time, the tissue remodels permanently, ensuring no further blood bypass occurs between the aorta and pulmonary artery.

In full-term, healthy infants, this process usually proceeds without a hitch. But in preterm babies or those with respiratory complications, the PDA may remain open longer, sometimes requiring medical intervention. Still, for the vast majority of newborns, the closure of the PDA is one of the quiet, unseen triumphs of early life—a small but essential step in adapting to the world outside the womb.