That dark greenish-black, gooey, sticky stuff in his diaper is called meconium, and it's made up of all the stuff baby was swallowing in-utero (amniotic fluid, lanugo, bile, mucus, dead skin cells — yummy). After a few bowel movements, baby will switch over to mustard yellow poop if you're breastfeeding. It will probably look as though it has seeds in it, and shouldn't smell very bad (score one for nursing!). Breast milk is digested fast, so baby might poop after almost every feeding at first. If you are formula feeding, baby's stool can be yellow, brown, or green, and will smell a little stronger.
See something weird in baby's diaper? If baby's poop is hard and pebble-like, red (could be blood), black (could be digested blood), or white (could signal a liver problem), give the pediatrician a ring. Any other colors are fine.
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