Parents and doctors often first notice something is wrong in the first days or weeks after birth when a baby shows rapid breathing, trouble feeding, or a bluish tint to the lips or skin because the lungs aren’t getting blood the usual way. A heart murmur or low oxygen readings during newborn checks can prompt an urgent echocardiogram, which reveals the abnormal origin of the right or left pulmonary artery from the aorta. In some cases, a prenatal ultrasound or fetal echocardiogram flags concerns before birth, but for many, the first signs of abnormal origin of right or left pulmonary artery from the aorta appear as newborn breathing difficulty and poor oxygen levels.