Preventing Birth Defects
Some types of birth defects are preventable. The causes of many types of birth defects are still unknown, but progress is being made in understanding how some birth defects can be prevented. Spina bifida and anencephaly, the two most common types of neural tube defects (NTDs), may be prevented if women have sufficient folic acid in their diet prior to becoming pregnant and during the pregnancy. Fetal alcohol syndrome (FAS) can be prevented if women do not drink during pregnancy. Some birth defects are caused by medications that are “teratogenic,” that is, they are known to interfere with fetal development. These medicines should be avoided when it is possible that a woman might become pregnant.
There are several things women can do to prevent birth defects:
- Take a multivitamin with 400 micrograms of folic acid every day, even if you are not planning a pregnancy.
- Eat a healthy diet with folate-rich foods and foods that have been fortified with folic acid.
- Do not drink alcohol if you are trying to become pregnant or at any time during pregnancy.
- Go for a pre-pregnancy health checkup. Review your prescriptions and any over-the-counter medications with your health care provider to determine if they are safe during pregnancy.
More about preventable birth defects:
- Neural Tube Defects (NTDs) and Folic Acid
- Fetal Alcohol Syndrome (FAS)
- Birth Defects caused by Medications and Other Substances
What are neural tube defects? The neural tube is the embryonic structure that develops into the brain and spinal cord. This structure, which starts out as a tiny ribbon of tissue, normally folds inward to form a tube by the 28th day after conception. When this process goes awry and the neural tube does not close completely, defects in the brain (anencephaly) and spinal cord (spina bifida) can result. Each year spina bifida and anencephaly, the two most common forms of NTDs, occur in approximately 1 of every 1,000 pregnancies in the United States and in an estimated 300,000 newborns worldwide.
Only recently have researchers made some progress in preventing these defects. The results of randomized trials now indicate that at least half the cases of neural tube defects could be prevented if women consumed sufficient amounts of the B vitamin folic acid before conception and during early pregnancy. For more information on spina bifida, go to Spina Bifida Association of America.
Who is at risk of having an NTD-affected pregnancy? Any woman can have an NTD-affected pregnancy. Women of Hispanic ethnicity are at slightly greater risk of having an NTD-affected pregnancy. In addition, women who have already had an NTD-affected pregnancy are more likely to have another NTD-affected pregnancy. Other risk factors include: maternal diabetes when the blood sugar is out of control, medicines (like some that treat epilepsy), obesity, and high temperatures in early pregnancy (such as fever that lasts a while, or using hot tubs and saunas).
What is folic acid? Folic acid, also known as folate, is a B-vitamin that can be found in some enriched foods and vitamin pills. Folate is the term for the naturally occurring form of the B-vitamin; “folic acid” is the synthetic form of the B-vitamin that you get in vitamin pills and in fortified foods. The body more readily absorbs folic acid from vitamin supplements and fortified foods than folate from food. According to the Institute of Medicine (IOM), the body only absorbs about 50 percent of folate, while approximately 85 percent of folic acid in fortified foods and 100 percent of the folic acid in a vitamin supplement are absorbed.
For more information on folic acid, go to Learn More about Folic Acid provided by the National Center for Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention.
How can I get enough folic acid? It is recommended that all women of child-bearing age (15-44) take a multi-vitamin and eat a healthy diet rich in folic acid. Women who have had gastric bypass surgery may be at greater risk of folic acid deficiency. Most multi-vitamins contain the recommended daily amount of folic acid, 400 micrograms. The following table gives examples of foods containing folate or folic acid:
|Folic Acid Can Be Found In These Foods|
|Dried beans and legumes||Cereals|
|Oranges and orange juice||Breads|
|Leafy green vegetables||Flour|
Women who already have had an NTD-related pregnancy are at much higher
risk of having another NTD-affected pregnancy. The U.S. Public Health
Service recommends that women with a prior NTD-affected pregnancy get
even more folic acid: 4,000 micrograms (mcg) daily beginning one month
before attempting to get pregnant and continuing through the first three
months of pregnancy. It is important that this is NOT done
by taking additional multi-vitamins. Typically, a health
care provider will prescribe one prenatal vitamin plus three 1 mg tablets
of folic acid a day to get this dosage. For additional information on folic acid see the MDH publication Minnesota's Folic Acid Guidelines for the Prevention of Neural Tube Defects (NTDs).
What is Fetal Alcohol Syndrome? Fetal alcohol syndrome (FAS) is a condition characterized by abnormal facial features, growth retardation, and central nervous system problems. It can occur if a woman drinks alcohol during pregnancy. Children with FAS may have physical disabilities and problems with learning, memory, attention, problem solving, and social/behavioral problems.
Who is at risk of having a baby with FAS? When a pregnant woman drinks alcohol, so does her unborn baby. There is no known safe amount of alcohol to drink while pregnant and there also does not appear to be a safe time to drink during pregnancy. Therefore, it is recommended that women abstain from drinking alcohol at any time during pregnancy.
Women who are thinking about becoming pregnant should stop using alcohol. Unfortunately, a woman may not realize she is pregnant for several weeks or more; this means that planning for your pregnancy is important. Since almost half of all births are unplanned, any woman capable of becoming pregnant should talk to her doctor about how to avoid exposing her baby to alcohol. If a pregnant woman has already used alcohol during her pregnancy, she should stop right away.
For more information, please go to the Fetal Alcohol Syndrome website sponsored by the Centers for Disease Control and Prevention.
Do medications cause birth defects? Some medications are known to cause birth defects. One example is Accutane® (isotretinoin), a medication used to treat severe nodular or cystic acne that has not responded to other treatments. It has been known to cause severe birth defects of the head, face, heart, thymus and central nervous system. Even though women taking Accutane® are required to use two forms of birth control, Accutane®-exposed pregnancies continue to occur and result in babies with major birth defects. Physicians should be knowledgeable about the teratogenic potential of Accutane® and actively assist their patients in preventing exposure during pregnancy. For more information on Accutane®, go to Key Findings from Recent Birth Defects and Pediatric Genetics Branch Projects provided by the National Center for Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention.
How do I find out if a medication or other substance causes birth defects? In addition to medications, there has been concern that some herbal products, infections and vaccines during pregnancy, maternal medical conditions, illicit substances, and other common exposures might increase the risk of birth defects. Substances that are known to interfere with fetal development and cause birth defects are called “teratogens.” More detailed information about some potential teratogens is available on fact sheets developed by the Organization of Teratology Information Services (OTIS)