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The Encyclo-poo-dia: Green, frothy or hard as pebbles? What your baby’s nappy is really telling you

The Encyclo-poo-dia: Green, frothy or hard as pebbles? What your baby’s nappy is really telling you

From Marmite meconium to yellow explosions, here's your no-nonsense guide to baby poo colours, textures and what’s worth worrying about.

Ruairidh Pritchard

Published: November 27, 2025 at 10:47 PM

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Forget what you thought parenting would be like — the real early milestone obsession? Poo.

It’s frequent, surprising, and, frankly, a bit weird. One minute it’s black and tarry, the next it's mustardy and seedy, and you’re wondering whether green poo means something terrible or just too much broccoli.

And while no one prepares you for how often you'll be inspecting nappies like a forensic scientist, knowing what’s normal (and what’s not) can make the whole experience a lot less stressful.

Here’s your reassuring, expert-backed guide to decoding your baby’s poo — no pictures needed, we promise.

What should my newborn’s first poo look like?

Colour: Black or very dark green
Texture: Incredibly sticky — like Marmite
Smell: None (weirdly)

This first poo is called meconium, and it’s not really poo at all. “It’s a mix of amniotic fluid, mucus, bile and skin cells that build up in the bowel during pregnancy,” explains family GP and mum-of-three Dr Philippa Kaye. “It’s really thick and sticky – so sticky, in fact, it can be hard to wipe off.”

Expect this within 24–48 hours of birth, then watch the colour lighten gradually over the first few days.

What happens next? Day 3 to 5 changes

As your baby starts digesting milk, you’ll see a shift from black to greenish, then yellow.

These are called transitional poos – and they’re totally normal. The meconium is clearing out, and you’ll likely see poos becoming softer, looser and more frequent — around four times a day, especially if you’re breastfeeding.

Breastfed vs formula-fed baby poo: what’s the difference?

Breastfed poo:

Runny, soft and sometimes curdled
Yellow with seedy bits
Sweet-smelling (ish)
Poo after nearly every feed (especially in the early weeks)

Breastmilk poo is really runny and soft – almost like diarrhoea

Dr Philippa Kaye

Formula-fed poo:

Firmer, smoother (think hummus)
Yellow, tan, green or brown
Smellier than breastmilk poo (but not adult-level)
Tends to be less frequent

How often should my baby be pooing?

Normal frequency varies a lot:

Newborns: Up to 5 poos a day
Breastfed babies: Can poo after every feed or once every few days
Formula-fed babies: Often poo less than breastfed babies
Solids stage: Typically once a day, but some babies go 2–3 days between

See your GP if your baby hasn’t pooed in over a week, especially if they’re formula-fed or seem uncomfortable.

Poo colour decoded: what’s normal and what’s not

baby poop colour chart, showing colours of baby poo in early days, plus green, yellow, brown, white, red and black poo and what they mean

Green poo:

Normal in many cases (especially if formula-fed)
Could signal a tummy bug, teething or foremilk imbalance in breastfed babies
Dark green and frothy? Might suggest your baby’s not getting enough hindmilk

Black poo:

After the meconium stage, black poo needs checking out. It could be digested blood or reaction to iron supplements.

If the poo is black like coal, do consult your GP

Dr Philippa Kaye

Red poo:

Could be blood – from birth, constipation, or allergies. Needs checking unless your baby has eaten beetroot.

White or pale grey poo:

Always worth a GP visit – could indicate a liver or bile duct issue.

Baby poo textures: what’s normal?

Normal textures:

Smooth and soft like purée or custard
Grainy or seedy (especially for breastfed babies)

When it looks unusual:

Frothy or bubbly poo

Often due to foremilk/hindmilk imbalance in breastfeeding. In formula-fed babies, could be an infection or allergy.

Foamy stools in breastfed babies may indicate something called lactose overload

Midwife Pip Davies

Mucus in poo

Small amounts are normal. A lot could mean a bug, allergy or teething — especially if baby is unsettled or unwell.

Hard, pellet-like poo

Usually constipation, more common in formula-fed or weaning babies. Try tummy massage, bicycle legs, fluids and fibre.

Watery poo

Could be diarrhoea — especially if frequent or accompanied by other symptoms. Monitor for dehydration and see your GP if:

Baby has fewer wet nappies
Has a fever or vomiting
Is under 8 weeks
Has 6+ watery nappies in 24 hours

What changes when baby starts solids?

Poo becomes browner, thicker, smellier
May contain bits of undigested food (totally normal)

You may notice what looks like undigested food – often peas or sweetcorn – but it’s not a concern

Dr Philippa Kaye

When to worry: baby poo red flags

Call your GP if you spot any of the following:

Black poo (after the first few days)
White, grey or chalky poo
Red streaks or blood in poo
Lots of mucus, especially with other symptoms
More than 4 watery poos in 24 hours
No poo for 7+ days
Threadlike worms in the poo

Final wipe

From runny mustard poos to worryingly green explosions, your baby’s nappies are a window into their health. The good news? Most of it is completely normal.

Now go forth, armed with knowledge — and many wipes.

Meet the experts

Dr Philippa Kaye is a GP, mum of 3 and author who regularly appears on ITV’s This Morning. Midwife Pip Davies is a practising NHS midwife and host of the Midwife Pip Podcast.

Remember, health content is not personalised medical advice. Consult a healthcare professional if you're concerned about your child's health.

Authors

Ruairidh PritchardDigital Growth Lead

Ruairidh is the Digital Lead on MadeForMums. He works with a team of fantastically talented content creators and subject-matter experts on MadeForMums.