Which statement correctly identifies the postnatal change of the foramen ovale?

• A. Ductus arteriosus
• B. Foramen ovale
• C. Umbilical vein
• D. Ductus venosus

Answer: (B)

The postnatal change of the foramen ovale is its closure after birth. In fetal life, it serves as a right-to-left shunt to bypass the nonfunctioning lungs. After birth, once the lungs fill with air, pulmonary blood flow increases and left atrial pressure rises while right atrial pressure falls. This pressure shift pushes the septum primum against the septum secundum, functionally closing the opening, and over weeks to months the two septa fuse to form the fossa ovalis. The other shunts you hear about—like the ductus arteriosus, umbilical vein, and ductus venosus—close as part of the transition to postnatal circulation, but they’re separate from the foramen ovale.