But after birth, we have a reversal of pressure. The left side is at a higher pressure than the right side. And what that means is inside the order, inside the systemic circulatory system, we're going to have a higher pressure than inside the pulmonary circulatory system. Now, what that means is as soon as that individual is born, normally what happens is as a result of that reversal and pressure, the foraminal valley essentially shuts close. And eventually, because the lungs are oxygenated and we produce a special type of protein known as bradycanin. Bradycanin uses that oxygen, goes into the ductus arteriosis and begins to constrict the ductus arteriosis, eventually closing that duct off.