Congenital: Definition, Birth Defects, Risk Factors, Diagnosis, Treatment and Prevention

It refers to any trait or condition present at birth acquired during intrauterine development.

A birth defect is a problem that occurs when a baby is developing in the womb. About 1 in 33 babies in the United States is born with a birth defect.

Birth defects can be minor or severe. They can affect appearance, organ function, and physical and mental development.

Most birth defects are present in the first three months of pregnancy, when organs are still forming. Some birth defects are harmless.

Others require long-term medical treatment. Serious birth defects are the leading cause of infant death in the United States, accounting for 20 percent of deaths.

What Causes Birth Defects?

Birth defects can be the result of:

  • Genetics.
  • Lifestyle choices and behaviors.
  • Exposure to certain drugs and chemicals.
  • Infections during pregnancy.
  • A combination of these factors.

However, the exact causes of certain birth defects are often unknown.


The mother or father can pass genetic abnormalities to their baby. Genetic abnormalities occur when a gene becomes defective due to a mutation or change.

In some cases, a gene or part of a gene may be missing. These defects occur at conception and often cannot be prevented. A particular defect can be present throughout the family history of one or both parents.

Non-genetic causes

The causes of some birth defects can be difficult or impossible to identify. However, certain behaviors greatly increase the risk of birth defects.

These include smoking, using illegal drugs, and drinking alcohol during pregnancy (doctors try to avoid harmful medications during pregnancy, so a pregnant woman should tell any doctor she sees that she is expecting). Other factors, such as exposure to toxic chemicals or viruses, also increase the risk.

If a mother has certain infections (such as toxoplasmosis) during pregnancy, her baby may have a birth defect . Other conditions that cause defects include rubella and chickenpox. Fortunately, many people get vaccinated against these diseases, so these infections are rare.

What are the risk factors for birth defects?

All pregnant women have some risk of giving birth to a child with a birth defect. The risk increases in any of the following conditions:

  • Family history of birth defects or other genetic disorders.
  • Drug use, alcohol consumption, or smoking during pregnancy.
  • Maternal age of 35 years or more.
  • Inadequate prenatal care.
  • Untreated viral or bacterial 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 of having a child with a birth defect.

Common birth defects

Birth defects are typically classified as structural or functional and developmental.

Structural defects occur when a specific part of the body is missing or poorly formed. The most common structural defects are:

  • Heart defects
  • Cleft lip or palate, when there is an opening or division in the lip or roof of the mouth.
  • Spina bifida, when the spinal cord does not develop properly.
  • Clubfoot, when the foot points inward rather than forward.
  • Sickle cell disease

Functional or developmental birth defects cause a part of the body or system to not work properly. These often cause intelligence or developmental disabilities .

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, which causes delayed physical and mental development.
  • Sickle cell disease, which occurs when red blood cells become misshapen.
  • Cystic fibrosis, which damages the lungs and digestive system.

Some children face physical problems associated with specific birth defects. However, many children show no visible abnormalities.

Defects can sometimes go unnoticed for months or even years after the child is born.

How are birth defects diagnosed?

Many types of birth defects can be diagnosed during pregnancy. A healthcare professional can use prenatal ultrasounds to help them diagnose certain birth defects in the uterus.

More comprehensive evaluation options, such as blood tests and amniocentesis (taking a sample of the amniotic fluid), can also be done.

These tests are generally offered to women who have higher-risk pregnancies due to a family history, advanced maternal age, or other known factors.

Prenatal tests can help determine if the mother has an infection or other condition that is harmful to the baby.

A physical exam and hearing test can also help the doctor diagnose birth defects after the baby is born.

A blood test called a newborn screen can help doctors diagnose some birth defects shortly after birth, before symptoms appear.

It is important to know that the prenatal exam does not always find defects when they are present. A screening test can also falsely identify defects. However, most birth defects can be diagnosed with certainty after birth.

How are birth defects treated?

Treatment options vary depending on the condition and the level of severity. Some birth defects can be corrected before or shortly after birth. Other defects, however, can affect a child for the rest of his life.

Minor defects can be stressful, but they generally don’t affect overall quality of life. Serious birth defects, such as cerebral palsy or spina bifida, can cause long-term disability or even death.

Talk to your doctor about the appropriate treatment for your child’s condition.


Medicines can be used to treat some birth defects or to reduce the risk of complications from certain birth defects. In some cases, medications may be prescribed to the mother to help correct an abnormality before birth.


Surgery can correct certain defects or relieve harmful symptoms. Some people with physical birth defects, such as a cleft lip, may undergo plastic surgery for health or cosmetic benefits. Many babies with heart defects will also need surgery.

Home care

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

How can birth defects be prevented?

Many birth defects cannot be prevented, but there are some ways to reduce the risk of having a baby with a birth defect.

Women planning to become pregnant should begin taking folic acid supplements before conception.

These supplements should also be taken throughout the pregnancy. Folic acid can help prevent spinal and brain defects. Prenatal vitamins are also recommended during pregnancy.

Women should avoid alcohol, drugs, and tobacco during and after pregnancy.

They should also exercise caution when taking certain medications. Some medications that are normally safe can cause serious birth defects when taken by a pregnant woman.

Be sure to tell your doctor about any medications you are taking, including over-the-counter medications and supplements.

Most vaccines are safe during pregnancy. In fact, some vaccines can help prevent birth defects.

There is a theoretical risk of harm to a developing fetus with some live virus vaccines, so these types should not be given during pregnancy. You should ask your doctor 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, need to take special care to monitor their health.

It is extremely important to attend regular prenatal appointments. If your pregnancy is considered high risk, your doctor may perform additional prenatal tests to identify defects. Depending on the type of defect, your doctor may treat it before the baby is born.

Genetic counseling

A genetic counselor can counsel couples with a family history of a birth defect or other risk factors for birth defects. A counselor can be helpful when you are thinking about having children or are already expecting.

Genetic counselors can determine the likelihood that your baby will be born with defects by evaluating family history and medical records. They can also order tests to look at the genes of the mother, father, and baby.