And that fetus develops a condition known as patent ductus arteriosis or PDA. That basically means that duct had not closed. Now, what will happen in such a case? Well, remember at birth, as we mentioned earlier, there is a reversal in pressure taking place. And so the pressure on the right side of the heart is lower than the pressure on the left side of the heart. And what that means is the pressure inside the systemic circulatory system is higher than the pressure inside the pulmonary circulatory system.