Birth Defect Types, Causes and Prevention Tips

Reviewed by Terri Forehand RN
Baby born with a cleft lip

Pregnancy can be an exciting time for families. It can also be a time of anxiety, and it's common for a woman to be concerned about the health of her unborn baby. According to the Center's for Disease Control, about three percent, or one out of every 33 babies, born in the United States suffers from some sort of birth defect. Most birth defects result in a physical or mental disability, and some can be fatal.

Common Defects In Newborns

According to Kids, a birth defect causes an abnormality in structure, function, or metabolism (body chemistry), and these defect fall into several sub-categories.

Structural Abnormalities

Structural abnormalities involve the baby's body having some missing parts or malformations. Examples include:

  • Spina bifida: This is a malformation of the spine which can result in paralysis below the level of the defect.
  • Cleft lip/cleft palate: These are oral malformations that occur early in a fetus' development, and they cause a split between the tissue of the lip or roof of the mouth.
  • Congenital heart defects: These include defects such as coarctation of the aorta, which is essentially a narrowing of the aorta that interferes with normal blood flow.
  • Defects of the genitals or urinary tract: These can include a malformed bladder, malformed ureters, and even ambiguous genitalia that make it difficult to distinguish if a baby is male or female.
  • Down's Syndrome: An extra chromosome leads to physical and developmental abnormalities.

Metabolic Abnormalities

Medline defines metabolic abnormalities as abnormal chemical reactions in the body that lead to illness or disease. Examples include:

  • Tay-Sachs Disease: A missing enzyme causes dangerous levels of ganglisides (fatty substances) to accumulate in the nervous system and interfere with its functions.
  • Phenylketonuria: A missing enzyme causes accumulation of elevated levels of phenylalanine, which is toxic to brain tissue and interferes with normal cognitive development.

Congenital Defects

Some defects are caused by viral and bacterial infections during pregnancy, usually during the first trimester. These infections can cause blindness, deafness, mental retardation, and bone defects. Examples of viral and bacterial infections that cause birth defects include:

  • Rubella: This is a highly contagious viral disease which can cause severe complications for unborn children, such as deafness, blindness, and developmental delays.
  • Sexually transmitted diseases: These include herpes and HIV, which can have devastating effects on unborn children and infants.
  • Cytomegalovirus (CMV): This. is a viral infection linked to birth defects such as hearing impairment and impaired intellectual or motor function.

Other Defects

The "other" category includes problems caused by alcohol and drug abuse, and Rh disease, or genetic issues. For example, alcohol and drug abuse during pregnancy can lead to serious body malformations. Rh disease is caused by an incompatibility between the blood of a mother and her baby. According to The University of Rochester Medical Center, babies born with Rh disease may have jaundice, anemia, and brain damage.

Causes of Birth Defects

The two main causes of birth defects are environmental and genetic. Sometimes a combination of genetic predisposition and environmental problems is at fault, such as with the defect known as clubfoot.

Clubfoot as an Example

Newborn with clubfoot; © AGLphotoproductions |

According to WebMD, the causes of clubfoot may be both environmental and genetic, but the exact cause is unknown. Scientists do know clubfoot is not caused by the baby's position in the womb. It is also known that certain behaviors of the pregnant mom, such as cigarette smoking, increase the risk of clubfoot. There is some evidence that clubfoot is associated with other congenital abnormalities, such as spina bifida, which supports the theory that an underlying genetic issue could be the cause.

Environment Causes

Environmental factors such as smoking, drug and alcohol abuse, infection, and exposure to certain medicines or other chemicals can cause problems in a developing baby. Examples include blindness, deafness, heart defects, and mental retardation.

Genetics Causes

Some genetic defects happen when the mother or father passes on an abnormal gene to the fetus. This is called dominant inheritance, and dwarfism is one example of this. Others defects develop when the mother and father both pass on the affected gene. This is called recessive inheritance, and examples include Tay-Sachs disease and cystic fibrosis.

There are also genetic defects which occur due to a problem with the number or structure of chromosomes, such as in babies born with Down Syndrome.

Improving Odds for a Healthy Baby

Before you get pregnant, make sure your vaccines are up to date, you are getting 400 to 800 folic acid a day (either in your diet or in a prenatal vitamin), and you have been tested to be sure you and your partner do not have any STDs.

After you get pregnant:

  • Do not smoke, drink alcohol, or take recreational drugs. Also try to avoid second-hand smoke, including marijuana.
  • Take a prenatal vitamin (that includes folic acid as mentioned above) to prevent against neural tube defects such as spina bifida.
  • Get early and consistent prenatal care.
  • Eat nutritiously and get plenty of appropriate exercise.

Even if you are very careful during the pregnancy, there's no way to guarantee that something won't go wrong during your baby's development. You can do everything right and still have a baby with a birth defect, but taking the precautions listed here can help increase the odds your baby will be healthy and normal.

Reach Out for Support

There are many different degrees of various birth defects. Some children have perfectly normal lives; others require a little more medical help and therapy, but they go on to have normal and healthy lives. There are also children who will require more extensive help to reach their full potential.

Support for Your Child

If your baby is born with a birth defect, rely on your physician and family for support. Thousands of families deal with birth defects in the United States, and joining a support group can be a good way to meet families like yours so you can share experiences and learn from each other. In addition, learn as much as you can about your baby's particular condition so you can make informed decisions regarding his/her care.

Support for You and Your Partner

Don't hesitate to get help caring for your other children or taking care of daily chores. You need to take some time for yourself and your partner. It may sound impossible, but taking care of yourself and your relationship will help you better care for your new baby.

Keep Your Focus Positive

Proper prenatal care can help prepare you for the best pregnancy possible. Be sure to consult your doctor if you have any concerns, and let him or her know right away if there's a family history of birth defects. Beyond that, there's no need to dwell on what can go wrong as long as you follow your obstetrician's advice. Just try to focus on staying healthy and getting ready for the baby to come. If you do learn your baby may have a defect, your doctor will provide you with information, care, and other resources to help you manage your situation.

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Birth Defect Types, Causes and Prevention Tips