Baby’s fontanel is flat under normal circumstances, but if it suddenly bulges and gradually becomes bulging and full, parents should be alert. The bulging fontanelle is commonly caused by the following reasons: First, the bulging fontanelle caused by intracranial infection, mostly seen in various meningitis, encephalitis and other diseases, due to intracranial infection resulting in increased intracranial pressure; Second, intracranial disorders resulting in bulging fontanelle, if the skull has a tumor, subdural fluid, blood accumulation, etc., can make the baby’s fontanelle gradually become full, resulting in bulging fontanelle; Third, the bulging fontanelle caused by drug factors. If you give your baby large doses of cod liver oil, vitamin A, tetracycline drugs for a long time, it can make your baby’s fontanel become full.