A Guide to Baby Poo and Wee: What Is Normal and When to Worry

Meconium

Your baby’s first poo is called meconium. It is thick, sticky, and almost tar-like. The colour is usually very dark green or black, and it can be quite surprising if you are not expecting it. Meconium is made up of everything your baby swallowed in the womb including skin cells, amniotic fluid, and tiny bits of lanugo. Babies usually pass meconium in the first 24 hours, and by day two or three, the nappies begin to change.

Transition to greenish or yellow poo

After the first couple of days, your baby’s nappies will shift from meconium to what we call the transition stage. The stools may become lighter, thinner, and can take on a brownish or greenish tone. This is completely normal and simply shows that your baby’s gut is starting to work with milk rather than relying on what they swallowed in the womb.

The transition stage usually lasts a few days before your baby’s nappies settle into a more predictable pattern.

Breastfed poo

Breastfed babies usually have soft, runny, mustard-yellow stools that can look seedy or grainy. The smell is quite mild and not unpleasant. In the early weeks, breastfed babies often poo several times a day, but after the first month some may only go every few days. As long as the stool is soft when it comes, that is completely normal.

Formula fed poo

Formula fed babies usually have firmer stools than breastfed babies. The colour is often pale brown, tan, or yellowish, and the smell can be a little stronger. Formula fed babies tend to poo less often than breastfed babies, and that is normal too.

Combi-fed poo

Combination feeding can produce a mixture of both. Babies may have slightly firmer stools than fully breastfed peers, and the colour can vary from yellow to light brown. Some green poos are also common with combi-feeding. The pattern can be less predictable, especially while your baby’s gut adjusts.

Normal colours

These are usually nothing to worry about.

Yellow Poo:

Very common in breastfed babies and completely normal. Runny, soft, or seedy textures are also normal.

Brown Poo:

Often seen in formula fed babies. Can be light or medium brown.

Green Poo:

Greenish poo is very common and usually harmless. It can appear for many reasons including fast letdown in breastfeeding, iron in formula, teething, or minor tummy viruses. As long as your baby is well and gaining weight, green poo is rarely a concern.

Warning signs

Certain colours deserve closer attention.

Red or blood streaks in baby’s poo:

Tiny streaks of blood can sometimes appear due to a small fissure or tear, especially if your baby has passed a firmer stool. However, if you see persistent blood, larger amounts, or if your baby is unwell, contact your GP or health visitor.

White, grey, or very pale stools:

These colours can indicate problems with bile flow and need urgent medical assessment. They are rare but important to recognise.
Black after the meconium phase:
Black stools beyond the first few days may signal bleeding higher up in the digestive system. Medical advice should be sough.

If you are ever unsure about a stool colour, take a photo and ask your health visitor, GP, or pharmacist. It is always better to check.

Runny or loose:

Soft, loose stools are normal in breastfed babies and are only concerning if there is an increase in frequency with signs of illness or dehydration.

Soft and formed:

Common in formula fed babies once their digestive system settles.

Thick or pasty:

Can be normal, especially during feeding transitions, but watch for firmness that causes discomfort.

Hard pellets:

These are a sign of constipation and may need support. If stools are consistently hard, contain blood, or your baby is straining and unhappy, speak to a professional.

Frequency

Baby poo frequency varies widely. Some newborns poo after every feed, while older breastfed babies may go days without a bowel movement. Formula fed babies often settle into a once a day or every other day pattern.

The key is comfort and consistency rather than how often it happens.

Common surprises include:

If you see mucus in the stool, occasional stringy patches can be normal, especially during teething or mild viruses. Persistent mucus or mucus alongside blood should be checked.

If your baby’s stool becomes very firm or they are struggling, look at fluid intake and fibre-rich foods such as pears, peas, prunes, and wholegrain options.

Wee gives us just as much information as poo. Most babies should produce several wet nappies a day once feeding is established.

What normal wee looks like:

What to watch out for

Signs of dehydration

Contact a health professional if your baby has:

Babies can become dehydrated quickly, so it is always better to ask if you are unsure.

Looking at nappies several times a day can feel overwhelming, especially in the early weeks. Here are some simple tips:

Keep a nappy diary

If you are concerned about feeding, weight gain, or hydration, jotting down wet and dirty nappies can be very helpful.

Trust your instincts

If something feels off, you are not being dramatic. Speak to your health visitor, GP, or pharmacist.

Stay calm

Babies can produce a wide variety of nappy surprises and most of them are perfectly harmless.

Reach out for support

You do not need to figure everything out on your own.

As a private health visitor, I support families through Essential Parenting, offering calm, personalised advice on feeding, poo and wee concerns, sleep, and overall wellbeing. You are always welcome to reach out if you would like one-to-one guidance.