A 20-day-old baby pooping once a day can be seen as a physiological phenomenon, which is normal at this time; pathological conditions (e.g. constipation) are abnormal. 1. Physiological phenomenon: for this age group, especially formula-fed babies, it is normal to have one bowel movement per day, but there are individual differences. For the above babies, if their bowel habits are similar to those in the past and there is no dryness in the stools, it is considered to be normal. 2. Pathological conditions: for babies who used to defecate more times a day, such as defecating 4~6 times a day, especially breastfed babies, the above phenomenon, the number of defecation is obviously less than the number of daily defecation, such as accompanied by dry stools, defecation difficulties, constipation can be considered to exist, as abnormal. 20 days baby poop once a day, there may also be other causes, it is recommended to go to the hospital in a timely manner, complete the examination to determine the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.