The baby's lips are blue, which is probably caused by the following three reasons: First, the baby has a history of trauma, because the baby is prone to fall after being in a more active age, and his lips will be bruised first. At this time, the lips will be obviously blue. Parents can judge whether the condition is serious by whether the baby is crying or not, and can let the baby take antibiotics and recover on its own. Second, the baby's blue lips are probably the manifestation of hemangioma, which is usually seen in newborn babies. Hemangiomas are congenital and can be diagnosed in maxillofacial surgery and then treated surgically. Third, bluing is probably caused by poor blood supply, which is likely to have something to do with the baby's heart. Parents can take their children to the cardiology department for relevant examinations. If the above three situations are excluded, it is probably just the baby's natural skin color, so parents need not worry too much.