You can't have a talk about RDS without one of these kind of slides, right. So this is one of those schematics that tells you about all the things that lead up to the problems that you see clinically. But the two big issues that we face are surfactant deficiency and structural immaturity of the newborn's lungs, and the big problem is that it leads to atelectasis, and that's what RDS really is, is atelectasis of the smaller airways. In those, the atelectasis results in inequality of perfusion and ventilation and hypoventilation, which leads to hypoxemia and hypercarbia, and that leads to respiratory and metabolic acidosis, and we have to treat the baby with high inspired oxygen and barotrauma, which causes endothelial injury, which leads to pulmonary vasoconstriction and inflammatory mediators, which leads to lung injury and RDS. So, it is just a lousy sequence of events, and as doctor Chibber was saying, what we want to do is sort of stop it at this point, and see if we can get the surfactant going to, hopefully, make the disease process a little less severe, and steroids is certainly a big help in that regard, antenatal steroids.