Baby's First Year · Breastfeeding

Is my newborn baby’s runny stool normal or is it diarrhea?

Father is changing baby's diaper

At the breastfeeding clinic, I have quite a few new parents expressing their concerns that their baby may be having diarrhea. I hear “my baby’s stool is liquid and runny” or “my baby has a bowel movement every time I change their diaper”.  On the other hand, some parents are not so concerned when their few days old infant has not passed a stool for more than one day.

So, what is the normal stooling pattern for a newborn baby? 

What are the normal colours of stool for a newborn baby?

First 2 days after birth:

  • the stool of breastfed babies is dark green or black in colour and has a sticky consistency. This first stool is called meconium.

After the second day:

  • the stool of breastfed babies gradually changes colour to brown/green/ yellow.

By day 5 or 6:

  • the stool changes to a mustardy yellow colour. These mustardy yellow stools may look curdy or “seedy”.

When breastfeeding is going well, it is expected that the baby will have 3 or more large soft stools each day during the first 5 or 6 weeks.  These stools are often described as having a yeast-like or slightly cheesy odour.

Your newborn baby should be seen by a doctor if:

  • There is no stool from your baby for more than 24 hours.
  • Your baby is still passing meconium on day five or six.
  • If you are worried about changes in your baby’s stool.

After 6 weeks, your baby’s stooling pattern may change.  Your baby’s stool may look thicker and you may notice that your baby does not have a stool for several days. As long as your baby’s stool is soft, it is completely normal for breastfed babies to have one very large yellow stool every 1 to 7 days.

If your baby is not exclusively breastfeeding and has been given infant formula, the stools may look darker in colour.  They may have a stronger smell and baby may pass stool less frequently.

You can access a free Toronto Public Health Breastfeeding Clinic if you have more questions about breastfeeding your baby.


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