Why is my child not growing as expected?

Is your child shorter or smaller than their friends, or have you noticed that their growth seems to have slowed down?

For parents of children with IBD, concerns about height and weight are common. Crohn’s disease and ulcerative colitis can sometimes affect growth, particularly when inflammation is active or a child is struggling to get enough nutrition.

But being smaller than other children does not automatically mean something is wrong.

Children grow at different rates, and genetics, puberty, nutrition and many other factors can influence height and weight. What matters most is often your child’s individual growth pattern over time.

📏 What does “not growing as expected” mean?

Growth isn’t simply about being tall or short.

Your child’s healthcare team may look at:

• height

• weight

• growth velocity — how quickly they are growing

• BMI, when appropriate

• their previous growth pattern

• their parents’ heights and family growth patterns

• puberty and development

• nutrition

• IBD activity.

A child who has always been smaller than their classmates but follows their usual growth curve may not have a growth problem.

On the other hand, a child who was growing steadily but suddenly starts growing more slowly may need further assessment.

The change in growth pattern can be more important than the actual number on the growth chart.

🩺 How can IBD affect growth?

Active IBD can affect growth in several ways.

Ongoing inflammation

Inflammation from active Crohn’s disease or ulcerative colitis can affect the body’s normal growth processes.

Not eating enough

Children may eat less because of:

• abdominal pain

• nausea

• diarrhoea

• feeling full quickly

• poor appetite

• fear of eating because food has previously caused symptoms.

Increased nutritional needs

When inflammation is active, the body may need additional energy and nutrients.

Nutrient deficiencies

Some children with IBD can develop deficiencies in nutrients needed for healthy growth, including iron, vitamin D, calcium, vitamin B12, folate and zinc.

Problems absorbing nutrients

Some children, particularly those with certain types of Crohn’s disease, may have difficulty absorbing nutrients properly.

Delayed puberty

If growth and nutrition have been affected, puberty can sometimes occur later. This can also make a child appear smaller than their peers for a period of time.

🍎 Could it simply be that my child isn’t eating enough?

Sometimes.

Children with IBD may struggle to meet their nutritional needs, especially during a flare.

They might:

• skip meals

• eat very small portions

• avoid foods they associate with pain

• have a poor appetite

• become full quickly

• avoid eating at school because of toilet worries.

However, poor growth shouldn’t automatically be blamed on picky eating or not eating enough.

If your child’s growth has slowed, their healthcare team may want to understand why before simply recommending that they eat more.

🔥 Could an IBD flare affect growth?

Yes.

A prolonged or poorly controlled IBD flare can affect appetite, nutrition and the body’s ability to grow normally.

Symptoms such as diarrhoea, abdominal pain, bleeding and fatigue can make eating difficult and increase nutritional demands.

If your child has a change in bowel habits, weight loss or other symptoms alongside slowing growth, tell their IBD team.

Sometimes growth changes can be an important clue that inflammation isn’t fully controlled — even when other symptoms seem relatively mild.

⚖️ What if my child’s weight is okay but their height isn’t increasing?

This is an important distinction.

A child can maintain their weight while their height growth slows. That’s why IBD teams generally monitor both height and weight over time.

Your child’s doctor may look at their growth velocity and compare it with their previous measurements rather than focusing on one appointment’s height or weight.

🌱 What about puberty?

Puberty naturally causes major changes in height, weight and body composition.

Some children with IBD may experience delayed puberty, particularly when they have had significant or prolonged inflammation or nutritional difficulties.

If your child seems to be developing later than their peers, don’t assume that IBD is definitely responsible.

Family genetics and normal differences in puberty timing are also important.

Your child’s doctor can assess whether their development is within the expected range.

🧪 What tests might be needed?

If your child’s growth is slower than expected, their healthcare team may review several things.

Depending on your child’s situation, this could include:

• growth measurements and growth charts

• weight and nutritional intake

• blood tests

• iron and ferritin

• vitamin D and other nutritional markers

• inflammatory markers such as CRP and ESR

• faecal calprotectin

• assessment of IBD symptoms and disease activity

• puberty and hormone assessment

• other investigations if needed.

Not every child will need all of these tests.

The aim is to work out whether the growth pattern is related to IBD, nutrition, puberty, genetics or another cause.

🥗 How can nutrition support healthy growth?

Children need enough energy, protein, vitamins and minerals to support normal growth. If your child isn’t gaining weight or growing as expected, an IBD dietitian can be particularly helpful.

They may recommend:

• increasing energy and protein in meals

• smaller, more frequent meals

• nutrient-rich snacks

• nutritional supplements when appropriate

• strategies for eating during a flare

• checking for nutritional deficiencies

• working around food intolerances or symptoms.

It’s important not to put your child on a restrictive diet without professional advice.

Removing large numbers of foods can make it even harder for a growing child to get enough nutrients.

💊 Can IBD treatment help growth?

If active inflammation is contributing to poor growth, controlling the underlying IBD is an important part of helping your child grow.

Your child’s gastroenterologist may review their treatment if inflammation is still active.

The goal isn’t simply to make your child gain weight or grow taller — it’s to control the underlying disease while supporting healthy nutrition and development.

Never change or stop your child’s IBD medication without speaking with their healthcare team.

❤️ How can I support my child?

Growth can become a sensitive topic, particularly as children get older. Try to focus on health, strength and development rather than body size.

You can help by:

• offering regular meals and snacks

• keeping food as positive and relaxed as possible

• avoiding comments about your child’s body or weight

• supporting their prescribed IBD treatment

• attending regular appointments

• keeping track of changes in appetite or symptoms

• asking for dietitian support when needed

• giving your child opportunities to talk about how they feel about their growth.

If your child is worried about being smaller than their friends, reassure them that children grow at different rates and that their healthcare team is keeping an eye on their development.

📞 When should I talk to the IBD team?

Contact your child’s IBD team if you notice:

• their height growth has slowed or stopped

• unexplained weight loss

• difficulty gaining weight

• a significant change in appetite

• persistent diarrhoea

• ongoing abdominal pain

• frequent vomiting

• blood in the stool

• significant fatigue

• difficulty eating

• signs of delayed puberty

• concerns about your child’s relationship with food or body image.

You don’t need to wait until the next routine appointment if you’re concerned about a noticeable change.

💛 Remember: every child has their own growth pattern

Being smaller than other children doesn’t automatically mean your child isn’t healthy.

What matters is how your child is growing over time and whether their growth, nutrition, puberty and IBD activity are progressing as expected.

If your child’s growth has slowed, it is worth raising it with their IBD team. They can look at the bigger picture and work out whether your child needs further assessment or additional nutritional or medical support.

You don’t have to work out your child’s growth on your own. Your IBD team and paediatric IBD dietitian can help you understand what your child’s growth pattern means and what, if anything, needs to be done.