Folic Acid Deficiency and Neural Tube Defect
Neural tube defects are severe birth defects of the brain and spine.
CDC urges all women of reproductive age to get 400 micrograms (mcg) of folic acid every day during pregnancy, in addition to consuming food with folate from a varied diet, to help prevent neural tube defects (NTDs).
NTDs occur when the neural tube does not close properly. The neural tube forms the early brain and spine. These types of birth defects develop very early during pregnancy, often before a woman knows she is pregnant.
The two most common NTDs are spina bifida (a spinal cord defect) and anencephaly (a brain defect).
Women who have already had a pregnancy affected by a neural tube defect should consume 400 micrograms of folic acid every day.
If you have already had an NTD-affected pregnancy, CDC recommends consuming 400 mcg of folic acid each day, even if you are not planning to become pregnant. When planning to become pregnant, CDC recommends consuming 4,000 mcg of folic acid each day starting 1 month before becoming pregnant and during the first 3 months of pregnancy.
Spina bifida
Spina bifida is a condition that affects the spine and is usually apparent at birth. It is a type of neural tube defect (NTD).
Spina bifida can happen anywhere along the spine if the neural tube does not close all the way. When the neural tube doesn’t close all the way, the backbone that protects the spinal cord doesn’t form and close as it should. This often results in damage to the spinal cord and nerves.
Spina bifida might cause physical and intellectual disabilities that range from mild to severe. The severity depends on:
The size and location of the opening in the spine.
Whether part of the spinal cord and nerves are affected.
Types of Spina bifida
The three most common types of spina bifida are:
Myelomeningocele
When people talk about spina bifida, most often they are referring to myelomeningocele. Myelomeningocele is the most serious type of spina bifida. With this condition, a sac of fluid comes through an opening in the baby’s back. Part of the spinal cord and nerves are in this sac and are damaged. This type of spina bifida causes moderate to severe disabilities, such as problems affecting how the person goes to the bathroom, loss of feeling in the person’s legs or feet, and not being able to move the legs.
Meningocele
With meningocele a sac of fluid comes through an opening in the baby’s back. But, the spinal cord is not in this sac. There is usually little or no nerve damage. This type of spina bifida can cause minor disabilities.
Spina bifida occulta is the mildest type of spina bifida. It is sometimes called “hidden” spina bifida. With it, there is a small gap in the spine, but no opening or sac on the back. The spinal cord and the nerves usually are normal. Many times, spina bifida occulta is not discovered until late childhood or adulthood. This type of spina bifida usually does not cause any disabilities.
Diagnosis
Spina bifida can be diagnosed during pregnancy or after the baby is born. Spina bifida occulta might not be diagnosed until late childhood or adulthood, or might never be diagnosed.
During pregnancy there are screening tests (prenatal tests) to check for spina bifida and other birth defects. Talk with your doctor about any questions or concerns you have about this prenatal testing.
AFP – AFP stands for alpha-fetoprotein a protein the unborn baby produces. This is a simple blood test that measures how much AFP has passed into the mother’s bloodstream from the baby. A high level of AFP might mean that the baby has spina bifida. An AFP test might be part of a test called the “triple screen” that looks for neural tube defects and other issues.
Ultrasound – An ultrasound is a type of picture of the baby. In some cases, the doctor can see if the baby has spina bifida or find other reasons that there might be a high level of AFP. Frequently, spina bifida can be seen with this test.
In some cases, spina bifida might not be diagnosed until after the baby is born.
Sometimes there is a hairy patch of skin or a dimple on the baby’s back that is first seen after the baby is born. A doctor can use an image scan, such as an, X-ray, MRI, or CT, to get a clearer view of the baby’s spine and the bones in the back.
Sometimes spina bifida is not diagnosed until after the baby is born because the mother did not receive prenatal care or an ultrasound did not show clear pictures of the affected part of the spine.
Treatments
Not all people born with spina bifida have the same needs, so treatment will be different for each person. Some people have problems that are more serious than others. People with myelomeningocele and meningocele will need more treatments than people with spina bifida occulta.
Causes and Prevention
We do not know all of the causes of spina bifida. The role that genetics and the environment play in causing spina bifida needs to be studied further.
However, we do know that there are ways for women to reduce the risk of having a baby with spina bifida both before and during her pregnancy.
If you are pregnant or could get pregnant, use the following tips to help prevent your baby from having spina bifida:
Take 400 micrograms (mcg) of folic acid every day. If you have already had a pregnancy affected by spina bifida, you may need to take a higher dose of folic acid before pregnancy and during early pregnancy. Talk to your doctor to discuss what’s best for you.
Talk to your doctor or pharmacist about any prescription and over-the-counter drugs, vitamins, and dietary or herbal supplements you are taking. Learn about medication and pregnancy »
If you have a medical condition―such as diabetes or obesity―be sure it is under control before you become pregnant.
Avoid overheating your body, as might happen if you use a hot tub or sauna.
Treat any fever you have right away with Tylenol® (or store brand acetaminophen).
Spina bifida happens in the first few weeks of pregnancy, often before a woman knows she’s pregnant. Although folic acid is not a guarantee that a woman will have a healthy pregnancy, taking folic acid can help reduce a woman’s risk of having a pregnancy affected by spina bifida. Because half of all pregnancies in the United States are unplanned, it is important that all women who can become pregnant take 400 mcg of folic acid daily.
What is anencephaly?
Anencephaly is a serious birth defect in which a baby is born without parts of the brain and skull. It is a type of neural tube defect (NTD). As the neural tube forms and closes, it helps form the baby’s brain and skull (upper part of the neural tube), spinal cord, and back bones (lower part of the neural tube).
Anencephaly happens if the upper part of the neural tube does not close all the way. This often results in a baby being born without the front part of the brain (forebrain) and the thinking and coordinating part of the brain (cerebrum). The remaining parts of the brain are often not covered by bone or skin.
How Many Babies are Born with Anencephaly?
Researchers estimate that about 1 in every 4,600 babies is born with anencephaly in the United States.1
Causes and Prevention
The causes of anencephaly among most infants are unknown. Some babies have anencephaly because of a change in their genes or chromosomes. Anencephaly might also be caused by a combination of genes and other factors, such as the things the mother comes in contact with in the environment or what the mother eats or drinks, or certain medicines she uses during pregnancy.
Getting enough folic acid before and during early pregnancy can help prevent neural tube defects, such as anencephaly. If you are pregnant or could get pregnant, take 400 micrograms (mcg) of folic acid every day. If you have already had a pregnancy affected by an NTD, you can speak with your doctor about taking a higher dose of folic acid before pregnancy and during early pregnancy.
Since the United States began fortifying grains with folic acid, there has been a 28% decline in pregnancies affected by neural tube defects (spina bifida and anencephaly).1
In order to get the recommended 400 micrograms of folic acid every day, a woman of reproductive age can take a supplement containing folic acid or to eat foods fortified with folic acid, or both, depending on her dietary habits.
CDC is dedicated to better understanding the causes of birth defects. Understanding the factors that are more common among babies with a birth defect will help us learn more about the causes. CDC funds the Centers for Birth Defects Research and Prevention, which collaborate on large studies such as the National Birth Defects Prevention Study (NBDPS; births 1997-2011), to understand the causes of and risks for birth defects, including anencephaly.
If you are pregnant or thinking about becoming pregnant, talk with your doctor about ways to increase your chances of having a healthy baby.
Diagnosis
Anencephaly can be diagnosed during pregnancy or after the baby is born.
During Pregnancy
During pregnancy, there are screening tests (prenatal tests) to check for birth defects and other conditions. Anencephaly would result in an abnormal result on a blood or serum screening test or it might be seen during an ultrasound (which creates pictures of the body). For more information about screening and confirmatory tests during pregnancy, visit CDC’s birth defects diagnosis web page.
After the Baby is Born
In some cases, anencephaly might not be diagnosed until after the baby is born. Anencephaly is immediately seen at birth.
Treatments
There is no known cure or standard treatment for anencephaly. Almost all babies born with anencephaly will die shortly after birth.
