It is common for newborn babies to spit up after feeding, especially if they are breastfed. This is usually due to their immature digestive systems. It is important to burp them during and after feedings, and to keep them upright for about 20 minutes afterward. If the spitting up persists for more than 24 hours or if your baby seems to be in discomfort, it is a good idea to consult a doctor for further advice.