In most cases, it is not normal for a 7-month-old baby to have a stool only once every few days. 7-month-old babies may have 2-3 stools a day because their stomach function is not yet well developed, but some babies may have a stool once every few days when they are in a normal state, such as when they have just added complementary foods and their bodies have not fully adapted to them or when they are eating less. If the stool is in good shape and there is no difficulty in passing stool, and if feeding or eating is not affected, it is normal for the infant to have a stool once in a few days. If infants often have a stool a few days, especially with dry and hard stool, defecation difficulties, may be constipation, mostly related to the following reasons: 1, supplemental food added unreasonable: If the dietary fiber content in the supplemental food is less, rice flour added more, may cause infants dry and hard stool, not easy to discharge. You can add the right amount of vegetables and fruits in the complementary food to increase the content of dietary fiber; 2, less intestinal peristalsis: if the infant activity is low or born with an inactive intestinal tract, there will also be a few days a stool, you can increase the amount of activity or appropriate massage abdomen to promote intestinal peristalsis, so that the stool as far as possible in a timely manner; 3, allergic reactions: if there are allergens in the complementary food caused by intestinal allergies, there will also be constipation 4, gastrointestinal diseases: intestinal flora disorders or gastric congenital intestinal diseases, etc., can also cause constipation in infants, found in a timely manner to the hospital to confirm the diagnosis and treatment.