Once in three days pooping in a nine-month-old baby may be normal, or it may be caused by constipation. It can be improved by adjusting the diet. September-age baby’s digestive function is not well developed, there may be a three-day poop phenomenon, if the general appearance, color is normal, there is no bloating, loss of appetite and other undesirable symptoms, this situation is generally a normal phenomenon. If the baby complementary food is added improperly, dietary fiber intake is insufficient, or drink less water, may lead to baby constipation, thus appearing three days once the phenomenon of stool. This situation is not normal, you need to properly adjust the complementary foods, eat more fiber-rich foods, such as apple puree, banana paste, etc., drink a moderate amount of water, maintain a certain amount of activity, to relieve the symptoms of constipation in babies. If a nine-month-old baby often poops once every three days, he or she should seek prompt medical attention and make adjustments as soon as possible to avoid adverse consequences.