What to Expect in the Nappy

The moment you introduce solid foods, your baby's nappies will never quite be the same again. Colours shift, smells intensify, textures change, and frequency can go in either direction. Most of it is completely normal — but knowing what to expect (and what to look out for) can save a lot of worry. This guide walks you through everything, stage by stage, with a visual chart to keep as a quick reference.

Why Do Stools Change When Solids Begin?

Before weaning, your baby's digestive system only had to process milk — a liquid that is almost entirely absorbed, leaving very little waste. Solid food introduces fibre, starch, complex proteins, and entirely new bacteria into a gut that has never encountered them before.

Three things drive the changes you will see:

• New ingredients: Pigments in food (beetroot, carrot, spinach, blueberries) pass directly into the stool and change its colour.
• Gut microbiome shift: New bacteria colonise the gut to help digest plant-based foods. This produces more gas, changes stool consistency, and intensifies the smell.
• Transit time adjustment: The gut has to learn how fast — or slowly — to move solid material. This is why some babies temporarily become constipated, while others have looser stools.

All of this is a sign that your baby's digestive system is doing exactly what it should: growing and adapting. The changes typically settle within a few weeks of each new food introduction.

The Four Things That Will Change

1. Colour

This is usually the first thing parents notice. Stools shift from the yellow/mustard of a milk-fed baby to a much wider spectrum of browns, greens, and oranges. The colour is almost always linked directly to what was eaten in the last 24–48 hours. A bright orange nappy after a sweet potato meal is entirely expected. See the chart below for a full colour guide.

2. Consistency

Stools become firmer and more formed as solids are introduced. The soft, seedy, or runny texture of a breastfed baby's nappy gives way to something closer to a thick paste, and eventually to a more formed stool by around 9–12 months. Some lumpiness and variation is completely normal.

3. Smell

Prepare yourself: this is the biggest change. Milk stools have a mild, almost sweet smell. Once solid foods begin, the gut bacteria that break down plant proteins and fibre produce sulphur compounds — the same ones responsible for adult-strength odour. This is normal and not a sign of illness.

4. Frequency

There is no single "normal" frequency. Some babies continue to poo multiple times a day; others settle into once a day or even every 2–3 days. What matters most is not how often they go, but whether the stool is soft and passed comfortably. A soft stool every three days is not constipation. A hard, pellet-like stool every day is.

You May Also See Undigested Food

Peas, sweetcorn, bits of carrot, blueberry skins — these often pass through whole, especially in the early weeks of weaning. This is completely normal. Babies' digestive systems are still learning to break down plant cell walls. It does not mean the food is not benefiting them.

A Word of Reassurance

Nappy anxiety is one of the most common concerns parents raise during weaning — and it is entirely understandable. The changes can be dramatic and unexpected. But the vast majority of what you will see in those first weeks and months is simply your baby's gut doing the remarkable work of adapting to a whole new way of eating.

The single most useful habit you can develop is to think back to what your baby ate 24–48 hours agobefore worrying about an unusual nappy. In most cases, you will find your answer there.

When in doubt, your health visitor is always a good first port of call — that is exactly what they are there for.

References & Further Reading

This guide draws on current UK clinical guidance and expert dietitian advice. The sources below are the ones we used to write this guide — and they are also great places to explore if you'd like to learn more.

1. Baby Poo — What to ExpectERIC — The Children's Bowel & Bladder Charity (UK)eric.org.uk/childrens-bowels/baby-and-toddler-poo/
2. Constipation and Breastfeeding — Best Start in LifeNHS (National Health Service, UK)www.nhs.uk/best-start-in-life/baby/feeding-your-baby/breastfeeding/breastfeeding-challenges/constipation/
3. Eating Well: The First Year — A Guide to Introducing Solids and Eating Well up to Baby's First Birthday (2024)First Steps Nutrition Trustwww.firststepsnutrition.org/eating-well-in-the-first-year
4. Feeding in the First Year of Life — SACN Report (2018)Scientific Advisory Committee on Nutrition (SACN) / UK Governmentwww.gov.uk/government/publications/feeding-in-the-first-year-of-life-sacn-report
5. How to Manage Constipation During WeaningThe Children's Dietitian (Lucy Upton, Registered Paediatric Dietitian)www.thechildrensdietitian.co.uk/blog/constipation