4 months old baby 3 days no bowel movement is certainly not normal, normal 4 months old baby usually about 1-3 times a day bowel movement, 3 days no bowel movement is usually to consider the digestive and absorption function is reduced, whether there is a weak spleen and stomach function, if this is the case you can take a little four mill soup oral regulating the function of the spleen and stomach. It is also important to consider whether symptoms of the digestive system are due to cold and flu, which requires close observation. It is also common for children to have allergies, especially food allergies, such as milk protein allergies that tend to cause difficulty in bowel movements. It is also important to note that some babies may have a micro-ecosystem imbalance, where the probiotics in the intestinal micro-ecosystem are relatively low causing indigestion, resulting in no bowel movement for 3 days.