If your baby is breast fed, his stool will probably be a mustard yellow color with what looks like seeds and an inoffensive odor (score another point for nursing!). Breast milk is easy to digest, and many breastfed babies will poop with almost every feed in the beginning. Formula-fed babies' stool can be yellow, brown or green, and tends to have a stronger odor. All babies poop less frequently as they grow — yours might even skip days. This isn't a problem as long as your baby's stool is soft when he does poop. If the stool is hard and pebble-like, red (could be blood), black (could be digested blood), or white (could be a sign of a liver problem), call your pediatrician. Any other color stool is fine and perfectly normal. Also call the doctor if your baby seems uncomfortable or isn’t eating normally. As your baby starts eating solid foods (generally around four to six months), look for stool consistency, frequency and color to change once again.