The newborn mouth froth is usually caused by the following two reasons: 1, the discharge of fetal inhalation of amniotic fluid, the baby was born before the inhalation of amniotic fluid, after birth through this way to discharge the body of amniotic fluid, some newborns nose will also appear purring sound, parents can let the baby is lying on its side, conducive to the discharge of amniotic fluid. 2, neonatal pneumonia, if the baby suffers from pneumonia, can be manifested as the mouth froth symptoms. The symptoms are mainly due to the physiological characteristics of the newborn’s trachea. The newborn’s trachea is short and narrow, funnel-shaped, when exhaling, the gas in the lungs through the short and narrow trachea, the trachea can be washed out of the mouth through the respiratory tract phlegm, gas through the dirty phlegm produced a lot of foam, coupled with the immature development of the newborn cough reflex, even if there is phlegm in the trachea, the cough symptoms are not obvious, the symptoms of mouth froth can appear.