Newborns suddenly a day without poop in most cases is normal, but do not rule out the possibility of indigestion, functional constipation and other reasons. 1. Normal physiological phenomenon: because the newborn is relatively small, the intestinal function is still not well developed, so the number of bowel movements is not fixed, most of the time the number of bowel movements is more, but occasionally there will be a day of no poop phenomenon, as long as the spirit of the current good, good sleep, eating milk is normal, it is a normal physiological phenomenon. 2. Indigestion: If a newborn baby eats too much will lead to indigestion, food stays in the intestines, which can cause the above symptoms, parents can massage the abdomen clockwise to promote intestinal peristalsis, which can help relieve. Can also be taken orally, such as compound pepsin powder to help digestion. 3. Functional constipation: mostly seen in formula-fed newborns, may be caused by drinking less water. You can give the baby appropriate water to increase intestinal water, but also can give lactulose and other laxatives, if necessary, can be used to help defecation. Newborns suddenly did not poop for a day, if there is no other abnormal symptoms, close observation can be, if accompanied by poor mental state, loss of appetite, etc., should seek medical attention. The above medications should be used in accordance with medical advice.