Birth Defects & Disorders

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A birth defect is a significant abnormality of appearance, structure, or function that is present at birth. Birth defects are common. Two percent to three percent of live-born infants show one or more significant defects at birth. This number increases to approximately five percent by 1 year of age due to the discovery of defects that were not obvious at birth.

A birth defect can be visibly obvious, an internal defect, or a chemical imbalance within the body:

  • An example of a visibly obvious defect could be the absence of an arm or a hemangioma (blood vessel birthmark) on the surface of the skin.
  • An internal defect could be a malformed kidney or a ventricular septal defect (a hole between the lower chambers of the heart).
  • An example of a chemical imbalance would be phenylketonuria (a defect in a chemical reaction of the body that results in severe mental retardation).

An individual can have a single birth defect such as cleft lip (a gap in the upper lip) or multiple birth defects such as cleft lip and cleft palate (a hole in the roof of the mouth) together, or even cleft lip and cleft palate with associated birth defects of the brain, heart, and kidneys.

Not all birth defects are detectable at birth. Some, such as sickle cell anemia (a defect in red blood cells that causes severe anemia and bone pain) might not become apparent until the child is several months old. A malformed kidney might take years to be discovered.

Some birth defects might remain silent for many years. For example, Huntington disease is an inherited condition in which affected persons live normal lives for decades. Then, during middle age, they develop dementia and loss of control of their arms and legs.


If your baby is born with a birth defect or other health condition, he may need special care at birth and later in life. You may be worried and have lots of questions. It’s OK to feel this way.

Birth defects are health conditions that are present at birth. They change the shape or function of one or more parts of the body. Birth defects can cause problems in overall health, how the body develops or how the body works.

Learn about birth defects and other health conditions, what they are and how they happen. Common birth defects include heart defects, cleft lip and cleft palate and spina bifida. Find out how to prevent certain birth defects and other health conditions. And learn what treatments your baby may need if he has one of these conditions.



Birth defects can be caused by genetic factors and by a variety of environmental injuries such as infection, radiation, and drug exposure during pregnancy. The majority of birth defects, however, are without detectable cause.

About 20 percent of birth defects are caused by genetic or hereditary factors. Every human body cell contains 46 chromosomes, and each chromosome contains thousands of genes. Each gene contains a blueprint that controls development or function of a particular body part. People who have either too many or too few chromosomes will therefore receive a scrambled message regarding body development and function.

Down syndrome is an example of a condition caused by too many chromosomes. Because of an accident during cell division, individuals with Down syndrome have an extra copy of a particular chromosome. This extra chromosome causes a typical group of birth defects to occur repeatedly in affected persons. Individuals with Down syndrome have mental retardation, muscle weakness, downward slant of the eyes, low-set and malformed ears, an abnormal crease in the palm of the hand, and birth defects of the heart and intestines.

With Turner syndrome, a disorder that s only women, a person lacks a particular chromosome. In the affected persons, this causes short stature, learning disabilities, and absence of ovaries.

Since each of the genes on the chromosomes controls the structure and function of a body part, people with defective genes will show defects in the corresponding body part. These abnormal genes often cause hereditary disorders that pass down within a family. Hemophilia (absence of a blood-clotting chemical) is a familial disorder caused by a defective gene. Other examples of familial gene disorders are cystic fibrosis (a disorder that causes progressive damage of the lungs and pancreas) and sickle cell anemia.

Defective genes can also be caused by accidental damage, a condition called spontaneous mutation. Most cases of achondroplasia (a condition that causes extreme short stature and malformed bones) are caused by new damage to the controlling gene.


All pregnant women have some risk of delivering a child with a birth defect. Risk increases under any of the following conditions:

  • family history of birth defects or other genetic disorders
  • drug use, alcohol consumption, or smoking during pregnancy
  • advanced maternal age of 35 years or older
  • inadequate prenatal care
  • untreated viral or bacterial infections, including sexually transmitted infections
  • use of certain high-risk medications such as isotretinoin and lithium

Women with pre-existing medical conditions, such as diabetes, are also at a higher risk for having a child with a birth defect.



There are more than 4,000 types of known birth defects. They’re typically classified as structural or functional/developmental. Structural defects are when a specific body part is missing or malformed. The most common structural defects are:

  • heart defects
  • cleft lip or palate (when there’s an opening or split in the lip or roof of the mouth)
  • spina bifida (when the spinal cord doesn’t develop properly)
  • clubfoot (when the foot points inward instead of forward)

Functional or developmental birth defects cause a body part or system to not work properly. These often cause disabilities of intelligence or development. Functional or developmental birth defects include metabolic defects, sensory problems, and nervous system problems. Metabolic defects cause problems with the baby’s body chemistry.

The most common types of functional or developmental birth defects include:

  • Down syndrome (causes delay in physical and mental development)
  • sickle cell disease (when the red blood cells become misshapen)
  • cystic fibrosis (damages the lungs and digestive system)

Some children experience physical problems associated with specific birth defects. However, many children show no visible abnormalities. Defects can sometimes go undetected for months or even years after the child is born.


Many birth defects can be diagnosed during pregnancy, depending on the particular type of birth defect. Prenatal ultrasounds can be used to diagnose certain birth defects in utero. More in-depth screening options, such as blood tests and amniocentesis (taking a sample of the amniotic fluid), may also be done. These tests are usually offered to women who have higher risk pregnancies due to family history, advanced maternal age, or other known factors.

Prenatal tests can help determine whether the mother has an infection or other condition that’s harmful to the baby. A physical examination and hearing test may also be used to diagnose birth defects after the baby is born. A blood test called the newborn screen can help diagnose some birth defects shortly after birth, before symptoms occur.

It’s important to know that prenatal screening doesn’t always find defects when they’re present. A screening test can also falsely identify defects. Most birth defects can be diagnosed with certainty after birth.


The topic of birth defects is a complicated and emotional one. It is complicated in that birth defects are common and can be caused by many different genetic and environmental factors. The fact that the majority of birth defects are without known cause is frustrating to both parents and doctors.

The topic is emotional in that parents are understandably deeply upset when they learn that their child has a serious birth defect. Many parents feel that medical science should be able to prevent, or at least identify in advance, all possible birth defects. They often feel that someone is at fault. Mothers might blame themselves. They might feel that they either did something that caused the defect or that they failed to do something that could have prevented it. This is almost never the case.

Sometimes parents feel that the obstetrician is at fault. (An obstetrician is a doctor who specializes in treating women during pregnancy, delivery, and recovery.) The parents might believe that the obstetrician could have ordered a test, prescribed a medicine, or done something differently to prevent the defect. This is usually not the case, but an honest discussion with the child’s doctor will indicate if any person is at fault.

Parents of a child with a birth defect should schedule several long discussions with the child’s doctor at times when both parents can be present. The parents and doctor should thoroughly discuss possible causes, testing, treatment, and referrals to specialists and support groups. Parents should continue these discussions and should continue asking questions until they are completely satisfied.


Treatment options vary depending on the condition and level of severity. Some birth defects can be corrected before or shortly after birth. Other defects, however, may affect a child for the rest of their life. Severe birth defects, such as cerebral palsy or spina bifida, can cause long-term disability or death. Mild defects can be stressful, but they don’t typically affect overall quality of life. Speak with your doctor about the appropriate treatment for your child’s condition.


Medications may be used to treat some birth defects or to lower the risk of complications from certain defects. In some cases, medication may be prescribed to the mother to help correct an abnormality before birth.


Surgery can be done to fix certain defects or ease harmful symptoms. Some people with physical birth defects, such as cleft lip, may undergo plastic surgery for either health or cosmetic benefits. Many babies with heart defects will need surgery.


Parents may be instructed to follow specific instructions for feeding, bathing, and monitoring an infant with a birth defect.


Many birth defects can’t be prevented, but there are some ways to lower the risk of having a baby with a birth defect. Women who plan on becoming pregnant should start taking folic acid supplements before conception. These supplements should also be taken throughout the pregnancy. Folic acid can help prevent defects of the spine and brain. Prenatal vitamins are also recommended during pregnancy.

Women should avoid alcohol, drugs, and tobacco during and after pregnancy. They should also use caution when taking certain medications and getting vaccinated. Some medications and vaccines that are normally safe can cause serious birth defects when taken by pregnant women. Make sure to tell your doctor about any medications (including over-the-counter drugs and supplements) you may be taking. You should also ask them which vaccines are necessary and safe.

Maintaining a healthy weight also helps reduce the risk of complications during pregnancy. Women with pre-existing conditions, such as diabetes, should take special care to manage their health.

It’s extremely important to attend regular prenatal appointments. Additional prenatal screening can be done to identify defects if your pregnancy is considered high risk. Depending on the type of defect, it may be able to be treated before the baby is born.