Why does my newborn have black poop?

Your baby's first stools should be thick, black, sticky deposits called meconium. While it's a far cry from the "poop" that will follow, and sometimes a challenge to clean off of your baby's delicate skin, meconium's role in clearing bilirubin makes it a welcome sign for your baby's well-being.

Meconium fills the lower bowel of all newborns. It gets its distinct color from bile, a fluid produced in the liver that aids digestion. In addition to bile, meconium contains amniotic fluid, lanugo (the fine hair that covers your baby’s body while inside your uterus), dead skin cells, mucus, and bilirubin. Most of these ingredients are harmless, but too much bilirubin in the blood can lead to jaundice. Jaundice is a common condition in newborns but can have serious consequences if the bilirubin level exceeds certain limits. 

The liver filters the bilirubin from the blood and excretes it into the bowel (gut) where it is removed from the body through the stools (in other words, it’s pooped out). Because meconium is chock full of bilirubin, early excretion is vital to preventing serious jaundice. 

It typically takes a day or two for the meconium to be expelled—provided your baby is feeding well. When babies are underfed, they stop pooping. This allows the bilirubin to be reabsorbed out of the stool and back into the blood and increases your baby’s risk of jaundice. 

Number and color are equally important when it comes to stools. You can be sure your baby is getting enough to eat if she is having three or more stools a day by day 3. Her poop should turn from black to green by day 3, and yellow (breastfed baby) or brown (formula-fed baby) by day 5. 

Remember, while meconium may be a challenge to clean off of your baby's delicate skin, its role in clearing bilirubin makes it a good thing for your baby's well-being!

For more on poop, see our slideshow.

Image courtesy of Together With Baby

Last updated February 13, 2021

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