An occasional loose stool is nothing to worry about, but if your baby's bowel movements suddenly change; that is, he poops more than normal and passes watery, mucus- or blood-streaked stools that are clear, yellow, green, or very dark, it's diarrhea. A newborn will normally poop up to eight or 10 times a day, and an older baby may poop anywhere from a couple of times a day to once or twice a week. Diarrhea will sometimes, but not always, have a foul smell.
A normal bowel movement from a breastfed baby who's not yet on solids is usually yellowish and on the soft or liquid side. (Many parents say these early poops smell like buttermilk). Because your baby's stools can change consistency and color depending on what he's eating or what's in your breast milk, your nose will usually tell you if something's wrong.
A formula-fed baby usually poops once or more a day and has yellow or tan bowel movements of a peanut butter-like consistency that may smell a bit. Formula-fed babies are more prone to the illnesses that cause diarrhea because they don't get the protective antibodies from breast milk.
Once your baby starts eating solids, his poop will firm up but will also change consistency based on what he's been eating — and start to smell more than before. If your baby's solid bowel movements start getting liquid again, it may be diarrhea.
While a severe case of diarrhea can alarm even the most unflappable parents, rest assured that in the U.S. most cases of diarrhea are relatively mild and don't pose a major health threat as long as your baby doesn't get dehydrated. If your baby is otherwise healthy and is getting plenty of fluids, the diarrhea will probably clear up in a couple of days. WAMP! VED!!!!