The hard stomach of full-month babies can be considered to be caused by lactose intolerance, intestinal inflammation, indigestion and congenital abnormalities of gastrointestinal development, and the specific conditions need to be analyzed. 1. Lactose intolerance: a child’s lactose intolerance can cause indigestion, leading to bloating, and a full-term baby’s stomach will be hard. 2. Intestinal inflammation: full-term infants use the bottle is not clean, long time vicious circle easy to breed bacteria, do not pay attention to dietary hygiene caused by intestinal inflammation, will cause abdominal distension, abdominal pain and diarrhea. 3. Indigestion: When you feed your child, you inhale too much gas, and more gas in the digestive tract will easily cause bloating. 4. Congenital abnormalities of gastrointestinal development: common intestinal stenosis and intestinal obstruction can cause abdominal distension, and the child’s stomach will be hard. Full-month baby stomach hard, there may be other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.