Who is Likely to Stutter?

original author: Tamara Pelletier, former student
revised by: Cindy S. Spillers, current web master

Incidence and Prevalence:

Stuttering seems like a hidden disability. People who stutter do not look much different from others and we can't really pick them out in a crowd. In any given crowd, how many people might stutter?

Current figures suggest that around 3 million Americans, or 1% of the population, stutter, and most of these are children. More males stutter than females, although this sex ratio does not distribute itself evenly across ages. At the age of 2 and 3 years, males and females seem to have an equal likelihood of stuttering. The sex ratio of males to females becomes 3:1 by the first grade, and 5:1 by the fifth grade, where it remains through adulthood. The age of onset and the age of recovery might contribute to this changing sex ratio. It seems that girls begin stuttering earlier than boys and recover earlier than boys. Additionally, girls are more likely to recover from stuttering than are boys.

Earlier in this century speech pathologists and other believed that stuttering existed only in industrialized cultures. We have since learned that this is not the case. Stuttering exists in virtually every country and cultural group investigated, with varying prevalence. In Canada, the United States, most European countries, and Japan, people who stutter make up about 1% of the population. In the West Indies, 3-4% of the population stutters. African countries seem to have the highest prevalence of stuttering with about 8-9% of the population stuttering.

Risk Factors:

There are predisposing cause of stuttering which can put some children at a higher risk of beginning to stutter than others. Three major risk factor seem to influencing the development of stuttering. First, the sex of the child is a factor in children who stutter. Boys are more likely to persist in their stuttering than are girls. Second, the age of a child influences the presence of stuttering. Stuttering can emerge at any age, but it is more likely to begin between 2 and 5 years. Third, heredity plays a role. A child has a greater risk for stuttering if any members of the family stutter.

Inheriting a predisposition to stutter may explain why stuttering runs in families. Various researchers have investigated the familial incidence of stuttering and the results of their studies vary widely. Anywhere from 20% to 74% of people who stutter have reported having a relative who stutters, whereas, the prevalence of stuttering in families with no one who stutters is approximately 3%.


Spontaneous recovery of stuttering is common in young children. Most studies investigating spontaneous recovery rely on parent reports or on reports of adults who no longer stutter. Few studies have followed young stuttering children to document how many recover from their stuttering and at what ages this recovery happens.

Studies have reported that approximately 65% of preschool children who stutter will spontaneously recover. This recovery will occur within two years of the onset of stuttering. The spontaneous recovery rate drops to about 18% for children who have stuttered for 5 years or more. Therefore, the length of time the stuttering is present has a correlation to the chances of recovery. If spontaneous recovery occurs, it will most likely happen within two years of onset. It is unlikely a child will recover without speech therapy if the stuttering is present for longer than 2 years.

The number of relatives who have recovered or who persist in stuttering may relate to an individual's chances of recovery. Children who have more relatives who have recovered from their stuttering have a higher likelihood of recovering themselves. Children who have more relatives who persist in their stuttering may have less likelihood of recovering on their own.

If the risk factors point to stuttering persisting in a child, the stuttering may undergo predictable developmental changes. If this happens, therapy may help the individual learn to manage their stuttering.

Revised December, 2000

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