If the monthly newborn baby stool was watery, mostly caused by abdominal cold, viral enteritis, as follows: 1, abdominal cold: after the abdominal cold, it will cause abdominal pain and abdominal intestinal peristalsis accelerated, when drinking in the milk is not digested in a timely manner, absorbed, and quickly discharged from the body, which will cause the stool was watery. In this case, parents should keep warm in time. For example, warm water bag hot compresses on the stomach, will play a good therapeutic effect; 2, viral enteritis: if infected with norovirus or rotavirus, these viruses can cause intestinal inflammation in newborns, which can also lead to stools in water.