A Paediatric Allergist’s Guide to Baby Poo
Baby Poop: What's Normal, What’s Not — Insights from a Paediatric Allergist
Baby poop is one of the most common concerns new parents bring up—and for good reason. It varies widely and can seem alarming if you're not sure what’s typical. This guide to baby poo aims to help parents understand what’s normal, when to seek advice, and how poop may relate to health, including allergies.
Why Newborn Poop Matters
As a paediatric allergist, I often review photos of unusual nappies. While it may seem unusual, these images help identify potential problems. Most of the time, newborn poop changes are harmless and not linked to serious issues like IgE-mediated allergies. However, when poop abnormalities are paired with symptoms like vomiting, rashes, hives, food aversion, or anaphylaxis, we investigate further.
In such cases, we may suggest oral food and drug challenges or consult a paediatric allergy specialist.
What Does Normal Baby Poop Look Like?
The appearance of baby poop depends on age, feeding type, and gut microbiome development. During the first year, it’s normal to see variations in colour (yellow, green, brown) and texture (runny, seedy, pasty).
Babies have rapidly developing gut flora—more bacterial than human by cell count. According to NIH research, the infant microbiome is shaped by delivery method, feeding type, antibiotics, vaccines, and other factors.
No two babies will have exactly the same gut microbiome—or the same poop.
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Baby Poop at Different Stages
Newborns (Days 1–3)
Meconium: Sticky, black, tar-like stools
1–2 poos per day increasing with feeding
If no meconium passes within 48 hours, seek medical evaluation
Breastfed Babies
Yellow to mustard, often seedy and runny
Frequency can range from 12 times a day to once a week
As long as the baby is growing and the stool is soft, this is normal
Formula-Fed Babies
Pale yellow to greenish-brown, pasty texture
Usually one poo per day, but every other day is also acceptable
Starting Solids (Around 4–6 Months)
Stools may change colour and texture
Undigested food (e.g. sweetcorn) is common
May poo 3–5 times a day at first, then settle to once daily
If allergies are suspected during weaning, consider food allergy testing.
Mucus in Baby Poop
Mucus in baby poop often looks like streaks of jelly or slime. On its own, it is rarely a concern. If your child is otherwise well and gaining weight, it usually does not require further action.
However, if it appears alongside eczema, asthma, or food allergies, consult a specialist. Learn more about eczema treatment, asthma in children, or pollen allergies.
Baby Poop Volume: Large or Small
Some babies produce huge nappies, others go days without a bowel movement. Both can be normal. What matters is whether the baby is gaining weight and appears comfortable.
When to Seek Medical Advice
Seek professional input if any of the following occurs:
No meconium within 48 hours of birth
Poor weight gain or faltering growth
White, red, or black stools (excluding beetroot or iron supplements)
Persistent diarrhoea that affects growth
Blood in stool, especially with cow’s milk exposure
Painful bowel movements or visible fissures
Severe rashes around the anus
Chalky white or very pale stools
Hard, pellet-like stools
Blood in the stool may be a sign of cow’s milk protein-induced colitis, which often resolves with dietary changes. Learn more about this via oral food challenge testing in the UK.
What About Toddler Diarrhoea?
Loose stools can persist for months or years without causing health issues—a condition known as toddler diarrhoea. If your child is otherwise thriving, it may not require treatment. However, persistent cases might benefit from immunotherapy or a food allergy assessment.
Key Takeaways for Parents
Newborn poop and baby poop vary widely
Most changes are harmless and reflect diet, development, or microbiome shifts
Use this guide to baby poo as a general reference
If you’re concerned, trust your instincts and seek expert advice
Explore More with London Allergy Consultants
At London Allergy Consultants, we support families through every stage of allergy testing and treatment. Whether you're dealing with food sensitivities, eczema, hay fever, or asthma, our paediatric experts are here to help.
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