Types of Birth Defects Explained
One area of major defects that is common occurs in the heart. Another common structural
defect is spina bifida. Two common metabolic defects are: Tay-Sachs disease and phenylketonuria (PKU).
Birth defects are abnormalities that occur in babies at birth involving structure, function or body
These abnormalities can lead to mental, physical disabilities or both. Birth defects can be minor, serious or
they can be fatal.
There are approximately 150,000 babies born every year in the United States with some kind of birth defect
according to the March of Dimes.
There are three causes for birth defects. Birth defects can be genetically caused, a result of something in the
environment or there may be unknown causes for the defect.
Metabolic defects and structural defects are those in which a body part is missing or is formed incorrectly or
can occur when there is a problem with how the body chemistry works.
One area of major defects that is common occurs in the heart. Another common structural defect is spina bifida.
Two common metabolic defects are: Tay-Sachs disease and phenylketonuria (PKU).
Metabolic birth defects involve a missing or incorrectly formed enzyme. A baby born with a metabolic birth
defect can have serious consequences including fatality.
Congenital birth defects are those that are caused by infections such as rubella, cytomegalovirus, syphilis or
Radiation Birth DefectsBirth Defect: Phenylketonuria (PKU)
This is a rare birth defect that can be detected by a heel prick blood test at birth. Left undetected PKU can cause mental retardation.
PKU is a genetic birth defect inherited from both parents. Babies who have PKU need a special formula (low-phenylalanine) to meet its nutritional needs that will compensate for the deficient or missing enzyme that is needed to process the essential amino acid called phenylalanine. The child will need to continue to a special diet as a child and as an adult.
Birth defects can also be caused by alcohol abuse during pregnancy as well as certain medications.
Birth defects can occur to babies who have healthy parents. The age of the parent has relatively little to do
with the occurrence of birth defects as babies have been born to young couples.
Birth defects also happen to couples that have followed all instructions given to them by the obstetrician
caring for the mom and still give birth to a baby with a birth defect.
Couples who have no family history of birth defects and who may have other healthy children can still have a
child with a birth defect.
According to the March of Dimes as many as 60% of all birth defects have no known cause so they cannot be
Chromosomal defects during the formation of egg or sperm can also cause birth defects such as Down syndrome.
Environmental causes of birth defects are when the mom-to-be is exposed to chemicals or diseases during her
pregnancy or she abuses alcohol or takes certain medications that can cause birth defects.
There can also be multifactorial birth defects when more than one cause can be identified such as neural tube
defects, cleft lip and palate.
In summary, birth defects can be attributed to defects in structure, function or body metabolism. Birth defects
can occur to couples whom have no family history of birth defects and to those who even have other healthy
There are some birth defects in which there is no known cause. Alcohol abuse and certain medications may be
causes for birth defects and some infections can also cause birth defects such as rubella - especially if exposure
is early in the pregnancy.