Facts and causes

Do you want to know more about stammering? This page will take you through what causes stammering, when stammering starts, gender differences, variability, how many children stammer and other facts.

What causes stammering?

  • stammering does not develop because of anything that parents have done or not done
  • it arises because there are subtle differences in the way that the neural pathways involved in speaking develop when children are very young
  • it tends to run in families. It is influenced by but not completely explained by genetics
  • it does not develop because a child is anxious – although if a child has a stammer then anxiety may exacerbate it
  • broader areas of temperament may have an influence. Some children who stammer appear to experience emotions relatively intensely and have difficulty regulating their emotions
  • other traits like being prone to worry, being highly sensitive, or being eager to get everything right probably make it harder to cope with having a stammer
  • some children have difficulties with their language skills and this can contribute. They may need more time to think of words or organise their ideas. Language difficulties may be masked by stammering
  • children are generally more likely to stammer when using longer and more complex utterances (especially when they are at the edge of their ‘linguistic comfort zone’), when they are speaking quickly (or feel they have to speak quickly) or when there is some other load on the system for them

When does it start?

Children usually start to stammer when they are between 2 and 5 years of age but it can start later than this. It may start gradually or quite suddenly. It can come and go, especially early on.

Do the same number of boys and girls stammer?

Stammering affects equal numbers of boys and girls to start with but girls are more likely to stop stammering over time so that later on there are about 4 or 5 times as many boys who stammer as girls.

Is it the same all the time?

Stammering varies immensely depending on the context of the situation. You may or may not see a child stammering in the way that parents see it, and a child may often speak without stammering in some situations but stammer in others. A child will probably not be able to say why they stammer less sometimes.

Do children stop stammering?

Stammering fades away naturally for a lot of young children (up to around 80% of the time). This tends to happen before they reach school. Some children will continue to stammer throughout their lives. About 1% of the adult population stammers.

How many children stammer?

  • about 5% of children stammer at some point
  • more recent research suggests that as many as 8% could be a more accurate figure
  • while many parents worry that stammering can have a negative impact on how well their child does at school, how able they are to express themselves, be themselves, follow a desired career or even be happy in their life, stammering does not have to limit these things
  • there are many many highly successful people, and famous people, in various walks of life who stammer

Other facts

  • there is no relationship between stammering and cognitive ability
  • people everywhere in the world stammer
  • making changes in a child’s environment helps. What can you do to make your classroom inclusive of communication difference and stammer-friendly?

How might stammering affect a child at school?

Teasing and bullying

  • children who stammer are more at risk of being bullied than children who do not stammer


  • children who stammer are more vulnerable to developing social anxiety than children who do not stammer
  • anxiety can be about what people might think of them or what they might do
  • children who stammer to have often had experience of being laughed at, having their speech commented on or mimicked and this helps to explain their worry about listener reactions now
  • when children or young people are anxious about the social consequences of stammering (when stammering feels risky or exposing) they will naturally hang back. We want them to become more confident and participate more but this is often a gradual process
  • try to notice and encourage small steps and show that, above all, you are interested in what they have to say

Time pressure

  • Time pressure and performance pressure or an audience both make speaking harder for children who stammer
  • Answering the register, reading aloud in class, answering questions in class, giving a talk to the class, speaking in assemblies or sitting oral exams are all potentially difficult situations for a child or young person who stammers.

Read more about children who stammer at primary school.

Read more about young people who stammer at secondary school.


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Sometimes you just need someone to talk to

Our Helpline, 020 3316 8100, is open during office hours (9am-5pm) and voicemail messages can be left when the office is closed.

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