What should I do if my newborn has diarrhea and yellow water? Diarrhea in newborns is a common phenomenon, but when diarrhea occurs along with milk flaps and yellow water, parents should pay attention to it. This condition can lead to dehydration and malnutrition in the child and can even be life-threatening. Below we discuss the causes and prevention methods of newborn diarrhea of milk valves and yellow fluid from four aspects. Imperfect development of the baby\’s digestive system The digestive system of a newborn is very fragile and easily affected by poor eating habits, infection or stress. When the digestive tract is not fully developed, breast milk or milk powder contains too much lactose, sucrose and sugar substitutes that are difficult to digest.