Until about 6 weeks of age, most babies pass stool two to five times per day. Some babies have a bowel movement after every meal. Between 6 weeks and 3 months of age, the frequency of pooping typically decreases. Many babies poop only once a day and some as infrequently as once a week. If you notice the stools suddenly increase in number or looseness, suspect diarrhea. If it lasts for 3 or more stools, stools contain mucus, blood, or smells bad, this points to diarrhea. Other clues to diarrhea are poor eating, acting sick or a fever. Newborn diarrhea is very runny and looks like it's made up of more water than solid food. It can be yellow, green, or brown, and often can seep or "explode" out of their diaper.