Poos and wees
10-minute read
Key facts
- The poo of breastfed babies is usually runny, yellow and doesn't smell bad.
- The poo of a formula-fed baby is firmer, darker brown and smellier.
- Your baby’s poo might look green sometimes.
- Diarrhoea is when your baby does a lot of loose, watery poos and it’s often caused by an infection.
- Babies under 6 months old should always be checked by a doctor if they have vomiting and diarrhoea, because they can easily get dehydrated.
What does normal baby poo look like?
It might not be fun but checking what is in your baby's nappy is important. It can tell you a lot about the health of your baby. Your baby's poo will look and smell different depending on if they are breastfed or formula-fed.
Breastfed babies’ poo is runny. It doesn’t smell bad.
Formula-fed babies' poo is firmer. It is darker brown in colour and smellier.
Some infant formulas can make your baby's poo dark green. If you change from breast to formula feeding, your baby's poos will become darker. They will change from runny to more like a paste.
The first 6 weeks
During their first 6 weeks of life, both breastfed and formula-fed babies have poo that is either yellow or green. Breastfed babies tend to have softer, runnier poo. The poo of formula-fed babies is a little bit firmer.
Your baby's first poo (or stool) is called 'meconium'. It’s sticky and greenish black.
After a few days the poo will change to a yellow or mustard colour.
In the next few weeks, you can expect the colour and shape of the poo to change. There is also a change in how often they poo each day.
If you are breastfeeding, there might be more variety in the nappy. This is because the mother’s diet can affect your baby's poo. Any medicines you are taking can also affect your baby’s poo.

Why is my baby's poo green?
Parents sometimes find different colours of green in their baby’s nappy.
Breastfed babies can make bright, frothy green poo. This can happen because they are getting too much foremilk. It can also happen if mum is swapping from breast to breast during feeds. Try feeding from just one breast at a time until the breast is drained. This can help to make sure your baby is getting the rich hindmilk.
If your formula-fed baby’s poo is green, it could just mean they are getting a lot of iron in their formula. Check the formula to see if it contains an iron supplement. Speak to your child health nurse or doctor about possibly changing the formula you use.
How often should my baby do a poo?
Some babies fill their nappies at or around every feed. Some, especially breastfed babies, can go for several days or even up to a week without doing a poo.
Both are normal. It's also normal for babies to strain or even cry when doing a poo. Your baby isn't constipated as long as their poos are soft, even if they haven't done a poo for a few days.
Is it normal for my baby's poos to change?
From day to day, and week to week, your baby's poos will probably change. They can change if your baby starts to have top-up formula feeds. If you notice a significant change of any kind, you should talk to your doctor or child health nurse.
Pale (white or near white) poos may be a sign of jaundice. If you're worried, speak to your midwife or child health nurse.
A single streak of blood in your baby’s poo could be a sign of constipation. If you see more than one streak of blood, you should see your doctor immediately.
It’s also a good idea to take your baby’s nappy, or a poo sample, to show the doctor.
How can I tell if my baby is constipated?
Sometimes parents think that their baby might be constipated. This concern can arise if the baby has not done a poo for a few days. You might get worried if your baby seems like they are straining when they do a poo.
Healthy babies under 6 months can sometimes strain and cry before doing soft poos. This is known as 'dyschezia'. It is not constipation unless their poos are also hard. If the poos are soft, it will resolve on its own.
As long as your baby's poo is soft, it's perfectly normal to go for a few days without doing a poo. You will also find that babies often strain or make noises when they poo. Sometimes they go red in the face and even cry when they are doing a normal poo.
Constipation can happen when a baby starts on solid foods. Signs of constipation include:
- hard and dry poo
- poo that is firm and pebble-like
- your baby being upset
- a small streak of blood
Seeing a streak of blood might be alarming. If they are constipated, they might have a little tear in their anus (the end where the poo comes out). You should see your doctor or child health nurse to have them checked out.
Fully breastfed babies shouldn't get constipated. Even if they are not feeding as often, their poo should still be quite soft. Constipation is more common in babies who are formula-fed. It's important to follow the directions on the container of formula. This is to make sure the mix of powder and water is correct.
How can I tell if my baby has diarrhoea?
When it comes to diarrhoea, it can be harder to tell, as baby poo is already quite soft. If a baby’s poo is more runny and more frequent than usual, it could be diarrhoea.
Some signs to look out for include:
- poo that is quite watery
- doing more poos than usual
- your baby is being unwell, especially if they are vomiting
- your baby not wanting to feed
If you think your baby has diarrhoea, speak to your doctor or child health nurse. Babies can easily become dehydrated if they don't get enough fluids.
Severe dehydration is a medical emergency and can be fatal. If your baby shows signs of severe dehydration, seek urgent medical attention.
CHECK YOUR SYMPTOMS — Use the Symptom Checker and find out if you need to seek medical help.
How often should my baby wee?
Your baby may urinate (wee) as often as every 1 to 3 hours or as infrequently as every 4 to 6 hours. If your baby is unwell, or it is very hot outside, your baby may wee smaller amounts or less often.
Your baby is getting enough breast milk or formula if they have 6 to 8 wet nappies a day. The wee should be pale and not smelly.
If your baby is weeing a lot less than usual, see your doctor.
What does baby wee look like?
Your baby’s wee should be light to dark yellow in colour. The wee will be darker when your baby is drinking less liquid. This is because the wee is more concentrated.
When should my baby see a doctor?
Weeing should never be painful. If your baby seems distressed when they wee, this may be a sign of an infection. It could also be another problem in your baby’s urinary tract. Other signs of a problem in the urinary tract can be:
- irritability
- vomiting
- drowsiness
- loss of appetite
Blood in your baby’s wee is not normal. If you see blood in your baby’s wee, you should contact your doctor. If there are any other symptoms, such as tummy pain or bleeding in other areas, your baby will need immediate medical attention.
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Resources and support
Learn more about gastroenteritis in children. This factsheet from the Royal Children’s Hospital is available in different languages.
For help with breastfeeding visit the Australian Breastfeeding Association website or call their helpline on 1800 868 268.
Ask your midwife, child health nurse or pharmacist for advice on choosing a baby formula.

Speak to a maternal child health nurse
Call Pregnancy, Birth and Baby to speak to a maternal child health nurse on 1800 882 436 or video call. Available 7am to midnight (AET), 7 days a week.
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Last reviewed: February 2025