There are two main types of birth defects: structural and functional/developmental.

Structural birth defects are related to a problem with body parts. Some physical problems include cleft lip or cleft palate, heart defects, such as missing or misshaped valves, and abnormal limbs, such as a club foot. They also include neural tube defects, such as spina bifida, problems that are related to the growth and development of the brain and spinal cord.

Functional birth defects are related to a problem with how a body part or body system works. These problems often lead to developmental disabilities and can include things such as:

Nervous system or brain problems - such as learning disabilities, mental retardation, behavioral disorders, speech or language difficulties, convulsions, and movement trouble. Some examples of birth defects that affect the nervous system include Autism, Down syndrome, Prader-Willi syndrome, and Fragile X syndrome.

Sensory problems - such as blindness, cataracts and other visual problems, and varying degrees of hearing loss including deafness

Metabolic disorders - involve a body process or chemical pathway or reaction, such as conditions that limit the body's ability to get rid of waste materials or harmful chemicals. Two common metabolic disorders are phenylketonuria (PKU) and hypothyroidism.

Degenerative disorders--are conditions that might not be obvious at birth, but cause one or more aspects of health to steadily get worse. For example, X-linked adrenoleukodystrophy (X-ALD), which was the focus of the movie Lorenzo's Oil, Rett syndrome, muscular dystrophy, and lysosomal disorders are examples of degenerative disorders.