Newborns spitting foam may be a physiological phenomenon, but it may also be due to thrush, neonatal pneumonia and other diseases. 1. Physiological phenomenon: for newborns, shortly after birth, at this time the swallowing function is poor, the depth of the oral cavity is shallow, so when there is saliva in the mouth is prone to spitting foam, if there are no other abnormalities, it is a normal physiological phenomenon. 2. Thrush: The occurrence of this disease is related to the over proliferation of Candida in the oropharynx, which is common in infants and young children or people with functional defects. Affected children will be irritable, crying, breastfeeding difficulties and other symptoms, so there will be the phenomenon of foamy mouth. 3. Neonatal pneumonia: If it is aspiration pneumonia, it is caused by inhalation of foreign bodies, such as fetal feces, amniotic fluid, milk, etc. If it is infectious pneumonia, it is caused by inhalation of foreign bodies. If it is infectious pneumonia, it is related to pathogenic microorganisms such as bacteria, viruses and fungi. The child will have symptoms such as increased cough, increased respiration, refusal to eat, fever, vomiting, wheezing, etc. Some of the children will have foamy mouth. If the foamy mouth of newborns is excluded as a physiological phenomenon, it is necessary to go to the hospital in time to clarify the specific cause.