And remember, inside that developing fetal heart, there's a higher pressure inside the pulmonary trunk than inside the order. And so what happens is most of that oxygenated blood will once again bypass the lungs, will be redirected away from the lungs and directly into the systemic circulatory system into the order. Now, a tiny bit of that blood will still make its way into the lungs. And that's important because the lungs do need a small amount of oxygen to keep on developing so that at birth, those lungs can actually function properly and efficiently. So these are the two lungs that are used by the circulatory system of that fetus to basically redirect blood away from the lungs. Now, what happens at birth?