3-month-old babies spitting bubbles may be oral development problems, oral diseases, pneumonia and other reasons. 1. Oral development problems: infants with imperfect oral development, more saliva, can not swallow in time, the mouth is full of saliva, spitting bubbles. 2. Oral diseases: if the infant has herpes stomatitis, oral ulcers and other diseases, oral secretions increase, pain and reluctance to swallow, there will be spitting bubbles and accompanied by crying. 3. Pneumonia: infant resistance is low, easy to infected bacteria, viruses caused by pneumonia, in addition to spitting bubbles, will be accompanied by coughing, fever, or worse, dyspnea, poor mental condition. Infants spitting up bubbles, need to be combined with its mental state, if accompanied by serious crying, or coughing fever and other symptoms, should immediately consult a specialist physician to assess the condition, to give reasonable diagnosis and treatment.