Black baby poop is thick, sticky, and tar-like, with a greenish-black color that can surprise new parents the first time they open a diaper. In most cases, this is completely normal. It’s called meconium, and nearly every newborn passes it within the first day or two of life. Outside the newborn period, black poop usually has a straightforward explanation too, though it occasionally signals something worth checking out.
Meconium: Your Newborn’s First Poop
Meconium is the very first stool your baby produces, and it looks nothing like what comes later. It’s greenish-black, extremely sticky, and has a thick, tar-like consistency that can be surprisingly difficult to wipe off skin. Many parents describe it as resembling motor oil or melted licorice.
This substance has been building up in your baby’s intestines throughout pregnancy. It’s made of swallowed amniotic fluid, mucus, bile, shed skin cells, and lanugo (the fine hair that covers a baby’s body in the womb). Because meconium formed before your baby started eating, it’s essentially odorless, which is one easy way to distinguish it from later stools.
Your baby should pass their first meconium within 24 to 48 hours after birth. Once they start drinking colostrum or formula, their digestive system pushes the remaining meconium out, and the color begins to change.
How Poop Changes in the First Week
After the initial meconium clears, you’ll notice a rapid shift in color and texture over just a few days. The stools transition from black to a dark greenish-brown, then to a lighter green, and finally settle into the color your baby will produce regularly. This transition phase typically takes three to four days.
Where it lands depends on how your baby is fed. Breastfed babies typically produce mustardy yellow poop that’s loose and slightly runny, sometimes with small seed-like flecks. Formula-fed babies tend to have darker yellow or yellow-tan stools with hints of green, and the texture is a bit firmer. Both are perfectly normal. Once your baby has moved past meconium, all shades of yellow, brown, and even green fall within the healthy range.
Black Poop After the Newborn Stage
If your baby is past the first week of life and you’re seeing black poop again, the most common cause is iron. Iron-fortified formula or liquid iron drops prescribed for anemia can turn stool a very dark green or black. This discoloration looks alarming but has no effect on your baby’s health. It will resolve once the iron source is removed or changed.
Once your baby starts eating solid foods (usually between four and six months), certain foods can also darken stool dramatically. Blueberries are a frequent culprit. They can tint poop so dark it looks almost black, especially in larger quantities. Blackberries, dark grape juice, and even certain brightly colored snacks can have the same effect when colors mix in the digestive tract. If the timing lines up with a new food, the stool color is almost certainly diet-related.
When Black Poop Is a Concern
Black, tarry stool appearing after the meconium phase and without an obvious dietary or supplement explanation is worth paying attention to. In older infants and children, truly black and sticky poop (sometimes called melena in medical settings) can indicate digested blood from somewhere higher in the digestive tract, like the stomach or upper intestines. Digested blood turns dark as it passes through the gut, which is why it comes out black rather than red.
A few things help you tell the difference between harmless and concerning black stool:
- Timing matters. Black poop in the first two to three days of life is meconium, not blood.
- Check supplements and diet. If your baby takes iron or recently ate blueberries, that’s the likely explanation.
- Look at the whole picture. Black stool paired with fussiness, refusing to eat, vomiting, a swollen belly, or unusual tiredness is more concerning than an isolated dark diaper with a baby who otherwise seems fine.
What Normal Poop Smells Like at Each Stage
Meconium is nearly odorless because it formed before your baby started digesting milk. Once feeding begins, breastfed and formula-fed babies both produce stool with some smell, though breastfed poop tends to be milder. The real change comes when solid foods enter the picture. After solids are introduced, stool becomes firmer, darker in color, and noticeably stronger-smelling. This is a normal part of the digestive system maturing, not a sign of a problem.
Cleaning Up Meconium
Because meconium is so sticky, regular wiping often feels like it’s just spreading it around. A thin layer of petroleum jelly or a barrier cream on clean skin before that first diaper change can make cleanup dramatically easier, since the meconium sticks to the cream instead of directly to skin. Warm water and a soft cloth work better than dry wipes for removing it. Most parents find that once the transition stools start, cleanup becomes much simpler.