Neural tube defects

What are neural tube defects?

Neural tube defects (also called NTDs) are birth defects of the brain and spinal cord. Birth defects are health conditions that are present at birth. They change the shape or function of one or more parts of the body. Birth defects can cause problems in overall health, how the body develops or how the body works.

A baby’s neural tube normally starts out as a tiny, flat ribbon that turns into a tube by the end of the first month of pregnancy. If the tube doesn’t close completely, an NTD can happen. NTDs can cause serious problems for babies, including death.

NTDs happen in about 3,000 pregnancies each year in the United States. Hispanic women are more likely than non-Hispanic women to have a baby with an NTD.

The two most common NTDs are spina bifida and anencephaly. Spina bifida affects about 1,500 babies a year in the United States. If your baby has spina bifida, the tiny bones of the spine don’t close completely, and part of the spinal cord pokes through the spine. Children with spina bifida may have paralyzed legs (not able to move) and problems controlling their bladder and bowel (going to the bathroom). Milder forms of spina bifida may cause fewer problems for children.

Anencephaly is one of the most severe NTDs. It affects about 1,000 babies each year in the United States. Anencephaly is caused when the upper part of the neural tube that forms the brain doesn’t close completely. Babies with this condition are missing major parts of the brain, skull and scalp. They do not survive long after birth, usually for just a few hours. Girls are 3 times more likely than boys to have anencephaly.

Taking folic acid before and during early pregnancy can help prevent NTDs in your baby. Folic acid is a B vitamin that every cell in your body needs for normal growth and development.

What causes NTDs?

We’re not exactly sure what causes NTDs. Experts think some may be caused by genetics. This means an NTD can be passed from parents to children through genes. Genes are part of your body’s cells that stores instructions for the way your body grows, looks and works.

NTDs also may be caused by things in your environment, which includes where you live, where you work, the kinds of foods you eat or have access to and how you like to spend your time. Some things in your environment can be harmful to a pregnancy, like certain drugs, cigarette smoke, air pollution and lead.

Are you at risk for having a baby with an NTD?

Any woman can have a baby with an NTD. But there are things that may make you more likely than other women to have a baby with an NTD. These are called risk factors.

 Your risk for having a baby with an NTD is higher if:

• You’ve had a baby with an NTD. If you’ve had a baby with an NTD, there’s a 2- to 3-percent chance of having a baby with an NTD in another pregnancy. A genetic counselor can help you understand your risk for having a baby with an NTD. This is someone who is trained to help you understand medical conditions that run in families, and how they can affect your health and your baby’s health.
• You or your partner has an NTD, your partner has a child with an NTD or someone in either of your families has an NTD. This means you have a family history of NTDs. Use the March of Dimes Family Health History Form to keep track of health conditions, including NTDs,that may run in your family. Fill it out and share it with your health care provider or genetic counselor.

Other risk factors for NTDs include:

• Taking certain anti-seizure medicines. Talk to your health care provider before you get pregnant about how the medicine may affect your pregnancy.
• Obesity. Some studies show that being obese increases your risk for having a baby with an NTD. If you’re obese, you have an excess amount of body fat and your body mass index (BMI) is 30 or higher. To find out your BMI, go to cdc.gov/bmi. Talk to your provider about getting to a healthy weight before pregnancy.
• Diabetes. If your diabetes is uncontrolled, you may be at increased risk for having a baby with an NTD. Eating healthy foods and being active every day can help you keep your diabetes under control.
• Using opioids in the first 2 months of pregnancy. Opioids are highly addictive drugs. Your provider may prescribe an opioid to you as a painkiller if you’ve been injured or had surgery. Common prescription opioids include codeine, hydrocodone and oxycodone. These often are sold and used illegally. If you take any opioid during pregnancy, it can cause serious problems for your baby, like premature birth and drug withdrawal called neonatal abstinence syndrome (also called NAS). If you’re pregnant and taking any drug or medicine that may be an opioid, tell your health care provider right away.
• A high body temperature early in pregnancy. This may be caused by a fever or by spending a lot of time in a hot tub or sauna. If you’re pregnant, stay out of hot tubs and saunas. If you do use them, limit the time to less than 10 minutes.

How can you help prevent NTDs in your baby?

Taking folic acid before and during early pregnancy can help prevent NTDs in your baby. NTDs happen in the first month of pregnancy, before you may know you’re pregnant. This is why it’s important to have enough folic acid in your body before you get pregnant.

Most women

To help prevent NTDs in your baby, take a vitamin supplement with 400 mcg of folic acid every day before getting pregnant. A supplement is a product you take to make up for certain nutrients that you don’t get enough of in the foods you eat. Start taking this amount of folic acid each day at least 1 month before pregnancy and through the first 12 weeks of pregnancy. Your folic acid supplement can be:

• A multivitamin. This is a pill that contains many vitamins and other nutrients that help your body stay healthy.
• A prenatal vitamin. This is a multivitamin that has nutrients you need during pregnancy. Your health care provider may give you a prescription for prenatal vitamins, or you can get them over the counter without a prescription.
• A supplement that contains just folic acid

Take a vitamin supplement with 400 mcg of folic acid each day, even if you’re not trying to get pregnant.

Women at high risk for NTDs

If you’re at high risk for having a baby with an NTD, it’s recommended you take 4,000 mcg of folic acid each day to help prevent an NTD. Start taking 4,000 mcg 3 months before you get pregnant through 12 weeks of pregnancy. You’re at high risk if:

• You’ve had a pregnancy with an NTD in the past.
• You or your partner has an NTD.
• Your partner has a child with an NTD.

Studies show that taking 4,000 mcg of folic acid before and during early pregnancy can help reduce your risk of having another baby with an NTD by about 70 percent. Ask your provider how to safely get this much folic acid. It’s not safe to take several multivitamins or prenatal vitamins because you can get too much of other nutrients, which may be harmful to your health. Your provider can help you figure out the best and safest way for you to get the right amount of folic acid.

Can you get folic acid from food?

Yes! You can get folic acid from foods that are fortified with folic acid. Fortified means a food has folic acid added to it. Check the product label to see how much folic acid you get in each serving. Look for the word “fortified” or “enriched” on labels on foods like: 

• Bread
• Breakfast cereal
• Cornmeal
• Flour
• Pasta
• Products made from a kind of flour called corn masa, like tortillas, tortilla chips, taco shells, tamales and pupusas
• White rice

Some fruits and vegetables are good sources of folic acid. When folic acid is naturally in a food, it’s called folate. Foods that are good sources of folate are:

• Beans, like lentils, pinto beans and black beans
• Leafy green vegetables, like spinach and Romaine lettuce
• Asparagus
• Broccoli
• Peanuts (But don’t eat them if you have a peanut allergy.)
• Citrus fruits, like oranges and grapefruit
• Orange juice (100 percent juice is best. This means one serving of juice is equal to one serving of fruit.)

It’s hard to get all the folic acid you need from food. Even if you eat foods that have folic acid in them, take your vitamin supplement each day, too.

Can you find out if your baby has an NTD before birth?

Yes. You can get prenatal tests (medical tests you get during pregnancy) called screening tests to find out if your baby is at increased risk of having an NTD. Screening tests for NTDs include:

• Maternal blood screening (also called a quad screen). It’s called a quad screen because it measures four substances in your blood. The test is done between 15 to 22 weeks of pregnancy. 
• Ultrasound. This test uses sound waves and a computer screen to show a picture of your baby inside the womb. You usually get an ultrasound at 16 to 20 weeks of pregnancy.

If a screening test shows an increased risk of NTDs, your provider may recommend a diagnostic test to find out for sure if your baby has an NTD. Diagnostic tests for NTDs include:

• Amniocentesis. In this test, your provider takes some amniotic fluid from around your baby in the uterus (womb) to check for birth defects, like NTDs, in your baby. You can get this test at 15 to 20 weeks of pregnancy.
• Detailed ultrasound of your baby’s skull and spine

If you find out that your baby has an NTD, talk to your health care provider to learn more about your baby’s condition and options for birth and treatment. For example:

• You can plan to have your baby in a hospital that specializes in caring for babies with NTDs. This way your baby can have any necessary surgery or treatment soon after birth.
• You can decide whether to have a vaginal or cesarean birth (also called c-section). During vaginal birth, the uterus contracts to help push the baby out through the vagina. A c-section is surgery in which your baby is born through a cut that your doctor makes in your belly and uterus. In some cases, a c-section may be safer for you and your baby than vaginal birth.
• If your baby has spina bifida, you can find out about surgery for your baby in the womb before birth. Surgery to repair spina bifida in the womb before birth is more effective than surgery after birth.

For more information

American Academy of Pediatrics

Spina Bifida Association

Centers for Disease Control and Prevention

Last reviewed: February, 2022