Why does my newborn have black poop?

Those thick, black, sticky deposits in your baby’s diaper are a far cry from the “poop” that will follow. But your baby’s first stools, known as meconium, are actually cause for celebration. 

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. 

For more on poop, see our slideshow.

Image courtesy of Together With Baby

Last updated June 5, 2017

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