Understanding Baby Poo

As a parent you will learn many new skills. One of these will be how to work out the different stages and meanings of your baby’s poo.

Let’s start at the very beginning.

Baby’s first poo

In utero, a baby swallows amniotic fluid. The fluid passes through their gut and when mixed with cells, water, lanugo (hair) and mucous, this becomes the baby’s first poo, known as meconium. This is a dark green, black, sterile, sticky substance which has no smell. Ideally, babies pass meconium within the first 24 hours after birth.

Once babies start breastfeeding, their poo changes from black to dark green, known as transitional poo, then to a bright yellow colour. Their poos may also contain small white fat curds which look like sesame seeds. If the baby is being fed on formula, their poo is usually more pasty and coloured khaki green. This is because of the iron contained in formula.

As long as the baby continues to gain weight, green poo is usually no cause for concern. However, sometimes green poo can also occur in babies who are unwell or are overfed, so it’s important to keep a close eye on your baby for other symptoms. Seek medical advice if you are unsure.

Poo patterns

Exclusively breastfed babies can poo before, during and after every feed. Don’t be concerned if your baby grimaces and strains when they are pooing. Even though they’re passing soft poos, it can take a while for their gut to become used to feeding, digesting and eliminating. The odd grunt is to be expected.

The best way to help a baby to poo is to continue with feeding. Babies have what is called gastrocolic reflex. As a baby sucks, their digestive tract contracts and moves milk along their gut. This stimulates the rectum to evacuate their bowel. Babies exhibit the gastrocolic reflex when they are feeding which commonly results in the baby passing wind, pooing or both.

Poo Colours and Shapes

The colour of newborn poo can change frequently, along with its texture and even the smell. Most babies will go through about 6 to 8 wet nappy changes a day and often, they poo at the same time. You’ll be spending more time than you ever imagined looking at your baby’s poo. It’s all part of the joy of having a newborn, especially as a normal poo can be a good sign of a healthy baby.

Learning what to look out for will help you understand your baby better. Here are some common types of poo and what they may mean:

Yellow poo

Runny, soft, yellow poo is the most common type of bowel movement for newborn babies, especially if they are breastfed. This is the normal way for poo to appear. Bright yellow, paler yellow and even mustard coloured poos are all within the range which is considered normal for breastfed babies. It’s also common for babies to have mucous in their poos.

Mustard poo

This is a colour range somewhere between yellow and orange, with a little brown thrown in! Mustard coloured poos are common in breastfed babies however, formula feeding can also cause poos to be a mustard colour. Often, mustard coloured poos are soft and pasty.

Orange poo

Orange coloured baby poo is common for babies who have eaten yellow - or orange-coloured fruits and vegetables. Sometimes small fibres of the undigested food are contained in their poo. Orange poos tend to be soft and pasty.

Green poo

Baby poo can be green for all sorts of reasons, most commonly when they’ve eaten green vegetables. But baby poo can also be green because of iron contained in baby formula, which is why green or khaki coloured poo is considered normal for formula fed babies. Breastfed babies can also have green poos, especially if they’re feeding often. Unless there’s other concerning signs, green poos are considered within the normal colour range.

Red poo

Red baby poo may be an indicator there is blood in the baby’s stool. Sometimes babies have mucousy, blood stained poos or poos which contain obvious spots or streaks of blood. Seek urgent medical advice if you notice blood in your baby’s nappy.

Brown poo

Brown poos are normal in older babies, especially once they’re used to digesting milk and solids.

Black poo

Black baby poo may indicate there could be bleeding high in the baby’s gut and the poo contains older, digested blood. Seek urgent medical advice to review further.

White poo

White baby poo may indicate issues with liver function. Have your baby seen by a doctor as soon as possible if their poos are white or pale

Frequently asked questions about baby poo

How would I know if my baby is constipated?

Constipation relates to the consistency of poo, not the frequency. So, even if your baby only poos every few days, as long as their poo is soft, they are unlikely to be constipated. Breastfed babies especially can have periods of up to a week between pooing. But as long as they are otherwise fine, thriving, gaining weight and seem comfortable, there’s unlikely to be anything to worry about.

Formula fed babies are more likely to become constipated. Dry, hard, pebbly poos are a sign that the poo has been sitting in their bowel for longer than ideal and much of the water has been reabsorbed. Check that you are preparing their formula exactly as directed on the can by the manufacturer. If your baby is old enough for solids, offer some extra vegetables and fruit to help boost their fibre intake.

How would I know if my baby has diarrhoea?

Diarrhoea stools are frequent, loose, watery and may smell offensive. Diarrhoea can be a symptom of a parasitic, bacterial or viral infection. Diarrhoea stools can be yellow or green, depending on the cause. It can also be a sign of malabsorption; this happens when the baby is unable to digest milk. Babies with diarrhoea are at risk of becoming dehydrated and it’s important to have them checked by a doctor.

Why is my baby constipated now they’ve started solids?

Solid foods are digested in a different way to milk. When babies first start on solids, their poos will often become less frequent and firmer. Offer your baby solids which contain fibre, such as fruits and vegetables. Extra breastfeeds or sips of cooled, boiled water for babies who are formula fed can help to boost fluid intake. Don’t be surprised if you see small pieces of undigested foods in your baby’s nappy. This is normal and commonly improves as their gut becomes more developed and they get better at digesting solid food.

Why is my baby’s poo green?

Baby poo is often green because of what they have eaten in the way of solids. Very young breastfed babies commonly have green poos, especially if they are having large, frequent feeds which don’t have enough time in their gut to be completely digested. Green poos are normal for formula fed babies due to the iron contained in formula.

Seeking Medical Advice

When seeking medical advice about your baby’s poo – take a fresh nappy with you or, a sample of their poo. It may also help to take photos of their soiled nappies to show the doctor.

Avoid giving your baby any medicine to treat diarrhoea unless it is prescribed by your doctor.

As your baby grow and develops, other bodily changes may change their poo. For example, teething can sometimes cause babies to have looser poos than they usually do. Or they may experience baby constipation. The more you become familiar with your baby’s poos and understand what is a normal pattern for them, the easier it will be to identify a potential problem.

If you are ever concerned about changes in your baby’s poo – seek medical advice.

IMPORTANT: These tips are intended to provide general guidance only, based on the colour of your baby’s stool and are not intended to be relied on as medical advice. If your baby is exhibiting any other symptoms, or you’re unsure of anything, please speak to your healthcare professional as soon as possible.

Reviewed and updated by Jane Barry, Midwife and Child Health Nurse, May 2024.