Newborn poop should be greenish-black, tarry, and sticky, resembling motor oil. This type of poop is called meconium and is made up of amniotic fluid, mucus, skin cells, and other things ingested into the uterus. After two to four days, newborns should have "transitional stools" that tend to be green and less tacky than meconium. Breastfed baby poop is considered normal when its a mustard yellow, green, or brown color. It is typically seedy and pasty in texture and may be runny enough to resemble diarrhea. Healthy breastfed stools will smell sweet (unlike regular bowel-movement odor). Formula-fed baby poop is typically a shade of yellow or brown with a pasty consistency that is peanut butter-like. Formula-fed babies also pass fewer, but bigger and more odorous stools than breastfed babies.

In summary, newborn poop should be greenish-black, tarry, and sticky, resembling motor oil. After a few days, the color and consistency of the poop will change depending on whether the baby is breastfed or formula-fed. If you are concerned about the color or consistency of your babys poop, it is best to contact your babys healthcare provider.