It is not normal for an 8-month-old baby to have a stool once every 3 days. It is reasonable for babies to have 1-2 bowel movements per day during this period. If occasionally once every three days, but the shape of the stool is good and defecation is not difficult, it is also normal, because the baby’s intestines are in the process of development, sometimes eat not much food, the residue is relatively reduced, there may be a situation of once every three days stool. However, if the baby frequently has the symptom of once every three days, it is not normal. If the stool is hard and difficult to defecate, constipation may occur, which may be due to the following reasons: 1, low intake of dietary fiber: less vegetables and fruits in the daily complementary diet, which will lead to insufficient intake of dietary fiber, which may cause a decrease in the number of stools and dry stools; 2, less activity: some babies have less activity, resulting in slower peristalsis of the intestines, which may also The situation of constipation may occur. You can appropriately increase the amount of activity, if the activity is inconvenient, parents can help to do abdominal massage, promote intestinal peristalsis, to promote the effect of defecation; 3, bad bowel habits: irregular bowel habits, can also cause bowel inhibition or defecation difficulties; 4, their own reasons: some babies add allergens in the complementary food, resulting in intestinal allergies may also appear constipation. In addition, some babies have intestinal development problems or low gastrointestinal activity, may also cause constipation, need to be appropriate intervention to avoid long-term constipation, affecting the child’s metabolic state and nutritional status.