Yellow, brown, green. Poop can be a blend of yellow, brown, and green colors. Babies older than a week usually have yellowish poops. Older kids tend to have brownish poops. Worrisome colors are red (blood), black (old blood), or grey/white (lacking in bile). A doctor should evaluate a child, if his or her poop is a worrisome color.
Most colors. Stool color changes with age and diet. Newborns have sticky black stools (called meconium) until about 4 days of life when the stool transitions to a yellow color. When you start introducing solids, stool color may change depending on what the baby ate. Black (older than newborn) and clay/white colors may indicate a problem. If you think there is blood in the stool you need to see a pediatrician.