Pervasive developmental disorder

Pervasive developmental disorders (PDD) are a group of disorders. There are five disorders in the group. These disorders all slow down the rate a child learns to talk and listen to others, as well as cause other problems.
The five disorders are:
The first three of these disorders are also called autism spectrum disorders. The last two are not common.
A child's parents might begin to notice signs of PDD when the child is a baby, and it usually appears before the child is three years old.