Birth Defects Explained

What are birth defects?

Birth defects are structural or functional abnormalities present at birth that cause physical or mental disability. Some may be fatal.

Researchers have identified thousands of different birth defects. Currently, birth defects are the leading cause of death for infants during the first year of life.

What causes birth defects?

Birth defects have a variety of causes, such as:

• Genetic problems caused when one or more genes doesn't work properly or part of a gene is missing

• Problems with chromosomes, such as having an extra chromosome or missing part of a chromosome

• Environmental factors that a woman is exposed to during pregnancy, such as rubella or German measles while pregnant, or using drugs or alcohol during pregnancy

What are the different types of birth defects?

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 hypothryroidsim.

• 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.

In some cases, birth defects are caused by a combination of factors. Some recognized patterns of birth defects affect many parts or processes in the body, leading to both structural and functional problems.