1. What is spitting up? Spitting up means that the baby regurgitates the milk he drank after feeding. This condition is more common in babies aged 0-12 months, especially in the first 3 months of life. Spitting up is not a disease, but if it happens frequently it may have an impact on your baby\’s health. 2. What are the causes of vomiting? 1. Immature digestion: The digestion of newborns is not fully developed, and food can easily reflux out of the stomach. 2. Improper feeding method: If the mother or nanny has incorrect posture or is too impatient when feeding, the baby will swallow too much gas, causing increased gastrointestinal pressure and causing reflux. 3.