3 months baby often spit often with swallowing function is not well developed, saliva secretion increased physiological factors, as well as respiratory tract infections, oral diseases and other pathological factors. 1. physiological factors: 3 months of the baby swallowing function is not yet developed, swallowing movement is not very coordinated, coupled with this time the salivary secretion began to increase physiological conditions, it will lead to the emergence of 3 months of the baby often spit out the situation. 2. Pathological factors: respiratory tract infections lead to 3 months baby sore throat, the baby may often spit, may also be due to oral ulcers or herpes and other oral diseases lead to the baby’s mouth pain, and then can not swallow saliva and other conditions lead to often spit. 3 months baby often spit, there may be other reasons, it is recommended to go to the hospital in time to improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.