Reasons why newborns always spit up milk after drinking milk. Infant spitting up is a common phenomenon, especially among newborns. Many new parents will encounter this problem, what should they do? First, you need to understand why newborns spit up milk frequently. The digestive system of newborns is not fully developed, and the gastrointestinal tract is too fragile and susceptible to external influences. In addition, babies who inhale too much air or have too much milk can also cause vomiting. Another situation is psychological factors