The main causes of spitting up in 14-day-old newborns are incorrect breastfeeding, indigestion and mechanical intestinal obstruction. 1. Wrong way of feeding: Only 14 days old newborns, their stomach in the horizontal position, and the lower esophageal sphincter is more relaxed, while the pyloric sphincter is relatively developed. Parents should not shake the newborn frequently or let the newborn head down when feeding, otherwise the newborn will spit up. 2. indigestion: 14 days newborn’s nervous system and digestive system is not yet fully developed, dominate the gastrointestinal tract peristalsis of the neuromodulation function is relatively poor, and the gastric mucosa secretion of gastric acid is relatively small, so the newborn’s digestive ability is relatively poor. If the newborn’s stomach is cold and he eats too much milk, he will easily suffer from indigestion, which will cause spitting up. 3. Mechanical intestinal obstruction: Mechanical intestinal obstruction can cause 14-day newborns to drink in the milk can not pass through the digestive tract smoothly. And the baby’s stomach capacity is relatively small, when the milk accumulates to a certain amount, it will produce spitting. 14 days newborn spit up, there may be other reasons, it is recommended to go to the hospital, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.