This pamphlet explains

types of birth defects common causes things you can do that may reduce your risk screening and diagnostic testing options for birth defects

Although some birth defects cannot be prevented, there are some things that you can do to reduce the risk of having a baby with a birth defect. Many involve making lifestyle and other changes before you become pregnant.

What Is a Birth Defect?

A birth defect is a problem that is present at birth and affects how the baby looks, functions, or both. A birth defect also is called a congenital disorder. More than 4,000 different birth defects are known, ranging from mild to severe.

Some birth defects can be seen right after the baby is born, such as a clubfoot or extra fingers or toes. Special tests may be needed to find others, such as heart defects or hearing loss. Some birth defects are not noticed until later in life.

Causes

Some birth defects are caused by errors in genes or chromosomes. Those caused by genes can be inherited—passed by parents to their children. Some inherited disorders are more common in certain ethnic groups, such as sickle cell disease, cystic fibrosis, and Tay–Sachs disease.

Chromosomal defects are caused by missing, damaged, or extra chromosomes. These defects are often the result of an error that occurred when the egg and sperm were joining. Common chromosomal disorders are Down syndrome and trisomy 18. Generally, the risk of having a baby with Down syndrome, trisomy 18, and other chromosomal disorders increases as a woman ages.

Other birth defects result from the fetus being exposed to harmful agents, such as medications, chemicals, and infections. Whether a woman or her baby is harmed depends on how much of the agent they have been exposed to, when during her pregnancy a woman is exposed to the agent, and for how long.

Sometimes, a mixture of factors is the cause. For many birth defects, the exact cause is not known.

Reducing Your Risk

Some birth defects cannot be prevented. But you may be able to decrease your risk of some disorders by taking certain steps.

See Your Doctor

If you are thinking about getting pregnant, visit your doctor first. Along with advice about diet, exercise, and other healthy behaviors, you can discuss your risks of having a child with a birth defect. Now is the best time to learn about the factors in your life that may have an impact on a pregnancy.

Know Your Risk Factors

Some people have risk factors for having a baby with a birth defect. You may be at an increased risk of having a baby with a birth defect if you

• are 35 years or older when the baby is due
• have a family or personal history of birth defects
• have previously had a child with a birth defect
• used certain medicines around the time you became pregnant
• have diabetes
• use illegal drugs or drink alcohol

Take a Daily Multivitamin Before Pregnancy

Folic acid—a form of a B vitamin—can help prevent neural tube defects. However, to be effective, it must be taken before pregnancy and up through the first 3 months. Because a woman may not know she is pregnant until later, it is recommended that all women of childbearing age get 0.4 milligrams of folic acid daily. An easy way to do this is to take a daily multivitamin that contains folic acid.

If you have had a child with a neural tube defect, you are more likely to have another child with this problem. You need an extra-high daily dose of folic acid—4 milligrams, or 10 times the normal preventive amount. Your doctor will prescribe a pill with this amount. You should not try to get this amount of folic acid by taking several multivitamins because high doses of the other vitamins in the pills may be harmful. Women with sickle cell disease or who take anti-seizure drugs also need this higher dose of folic acid.

Maintain a Healthy Weight

Women who are obese before becoming pregnant are at increased risk for having babies with birth defects. Obesity is defined as having a body mass index (BMI) of 30 or greater. Among the most common obesity-related birth defects are neural tube defects, heart defects, and abdominal wall defects. It also may be more difficult to diagnose fetal defects with ultrasound when the mother is obese. In addition to birth defects, obesity is linked to many pregnancy problems, including gestational diabetes, preeclampsia, cesarean deliveries, and infections.

Being at a healthy weight before becoming pregnant benefits both mother and baby. For most overweight women, combining a healthy diet with regular exercise is the key to weight loss. For women who are very obese (who have a BMI of 40 or greater), bariatric—or “weight loss”—surgery may be an option. Talk with your health care provider about when you would like to become pregnant and your weight loss goals. Together, you can devise a weight loss program that is right for you and that fits with your pregnancy plans.

Stop Smoking

Smoking has been linked to pregnancy problems, such as problems with the placenta and premature rupture of membranes. Health risks for infants born to a mother who smoked during her pregnancy include sudden infant death syndrome, hospitalization, and developmental problems. Even exposure to secondhand smoke can be harmful during pregnancy and to a newborn baby.

If you are thinking about becoming pregnant, stop smoking. If you have tried to quit on your own and failed, tell your health care provider. Many programs are available to help you stop smoking, including online groups. If you are a heavy smoker, nicotine patches or gum may help. However, the safety of these aids during pregnancy is not known. They should be used during pregnancy only if the benefits outweigh the possible risks.

Take Care of Medical Conditions Before Pregnancy

Women who have medical problems, such as diabetes or epilepsy, need to take special care of themselves. Birth defects are more common in babies whose mothers have these conditions.

If you have a medical condition, seeing your health care provider before you become pregnant is important. Ask what changes you need to make in diet, medication, or other areas to bring your condition under control before you try to get pregnant. For example, people with diabetes have high levels of sugar (glucose) in their blood. This extra glucose can damage organs in the mother’s body as well as in her baby’s body. Keeping glucose levels at or near normal levels with diet, medication, and exercise before pregnancy can help reduce the risk of birth defects.

Do Not Use Alcohol or Illegal Drugs

Alcohol use during pregnancy is a leading cause of mental retardation and other birth defects. One of the most serious effects of drinking during pregnancy is fetal alcohol syndrome. It is not clear how much, if any, alcohol is safe to drink during pregnancy. For this reason, pregnant women should avoid drinking any alcohol.

A Checklist For Reducing Your Risk of Birth Defects See your doctor before becoming pregnant. Know your risk factors. Take a daily multivitamin before pregnancy. Maintain a healthy weight. Stop smoking. Take care of medical conditions before pregnancy. Do not use alcohol or illegal drugs. Prevent infections. Avoid harmful agents, and learn about fish precautions. Be careful with vitamin A. Use medications wisely.

Use of illegal drugs can harm your baby. Many are highly addictive and a user’s lifestyle can be just as harmful as the drug itself. Some illegal drugs cause growth problems in the baby; others may cause brain injury and long-term emotional, behavioral, and learning problems. Many drugs increase the risk of preterm birth and other serious birth problems. Avoiding illegal drugs before and during pregnancy is critical to your and your baby’s health.

Prevent Infection

Rubella (German measles) during pregnancy can cause deafness, mental retardation, heart defects, and blindness in a newborn. There is a vaccine against rubella, but it should not be given while you are pregnant. If you have not already had the disease or been vaccinated, you should be vaccinated against rubella and wait at least 1 month before becoming pregnant. A test to see if you are immune to rubella can be done if you are not sure you have been vaccinated or had the disease. All pregnant women receive this screening at their first prenatal visit.

Toxoplasmosis is a disease caused by a parasite that lives in the soil. You can become infected by eating raw or undercooked meat or unwashed vegetables or by coming into contact with animal feces, especially from cats. Cats that go outdoors and hunt prey can carry the disease. If you are infected for the first time while you are pregnant, you can pass the disease on to your baby. Toxoplasmosis can cause birth defects, including hearing loss, vision problems, and mental retardation. To protect against toxoplasmosis, make sure that you eat well-cooked meat and wear gloves while gardening or handling unwashed vegetables. If you have an outdoor cat that uses a litter box, have someone else empty it, or use gloves and wash your hands well after doing so.

Sexually transmitted diseases (STDs) can cause serious birth defects. For instance, syphilis or herpes infection can cause severe problems in infants, including blindness and death. You will be tested for some STDs at your first prenatal care visit. Depending on your and your partner’s health history, you may be tested again for some STDs later in pregnancy. Treating an STD may prevent or reduce damage to the fetus.

Cytomegalovirus (CMV) is the most common viral infection in newborn babies. Most CMV infections cause no significant problems, but in severe cases the infection may cause mental retardation, deafness, and loss of vision. The risk of the fetus getting infected is greatest if a woman is infected for the first time when she is pregnant. If a pregnant woman has been exposed to the virus, a lab test can be done to find out if she has the infection. Pregnant women often get CMV from young children. The best way to prevent CMV infection is to wash your hands often, especially after contact with a child who is in day care

Avoid Harmful Agents

Exposure to toxic agents such as lead, mercury, or radiation can cause birth defects. Some women may be exposed to these agents at work. Some harmful agents are found in the home. Some are even in the food we eat. Not all of the harmful agents are known.

Because not all of the agents that can harm a developing fetus are known, it is important to keep safety in mind when using chemicals:

• Store chemicals in sealed containers when they are not in use.
• Wash hands after contact with hazardous substances and before eating or drinking.
• Avoid skin contact with chemicals.