There are several kinds of developmental delays a child may experience, some of which have biological causes, others may be environmental in nature. Such delays can be grouped into mental, physical, behavioral and speech.

• Mental (or cognitive) delay is related to intellectual function and learning disabilities but also affect communication and interaction. It can be caused by brain injury or chromosomal disorder.
• Physical delays can cause the slow development of motor skills, either coordination of the large muscle groups – arms and legs, or small muscle – the hands and fingers. Genetic conditions may also play a part here.
• Behavioral delays can affect social and emotional processes. They may result from autism spectrum disorder and attention deficit hyperactivity disorder. They will affect a child’s ability to learn and interact.
• Finally, speech development delays can be a sign of several other developmental deficiencies or can result from them. They may also result from either physiological causes or environmental.