It can take time for children to develop speak properly, and slight delays in the development of some speech abilities are not uncommon. However, in some children a lengthier delay may be caused by a speech disorder.

There are a number of speech disorders that can affect the development of your child’s ability to speak. If you’re concerned your child has a speech disorder, your doctor may refer you to a pediatric neurologist or a speech therapist. Here are three of the most common speech disorders that occur in children.

1. Articulation Disorder

This speech disorder causes children to mispronounce certain sounds such as S or R. Difficulty pronouncing S is called a lisp and is the most common type of articulation disorder. Those who have difficulty pronouncing R, commonly substitute it with W or U sound, such as pronouncing rubber as “wubbuh.”

Difficulties with articulation are common in very young children, but is considered a disorder if still present after a certain age. If you’re concerned your child’s articulation is caused by a speech disorder, consulting with a speech therapist is commonly the first step.

2. Stuttering

Stuttering is a speech disorder that causes involuntary pauses and repetition when your child speaks. While the precise causes of stuttering are still not completely understood, it is often picked up early on when learning how to speak. Stuttering can be caused by brain trauma.

3. Fragile X Syndrome

An inherited genetic condition, Fragile X Syndrome (FXS) makes it difficult for a child to express themselves through speaking. Children with FXS are more likely to also be diagnosed with autism. FXS also tends to affect boys more often than girls.