What Are Neural Tube Defects and How Can You Prevent Them?
Key takeaways:
Neural tube defects affect how the spine, spinal cord, skull, or brain forms and grows.
Neural tube defects develop early in a pregnancy, sometimes even before you realize you’re pregnant.
Folic acid supplements can help lower the risk of a neural tube defect. Experts recommend taking folic acid supplements even before you become pregnant.
Table of contents
Neural tube defects are a type of birth defect that develop during early pregnancy. Unlike many birth defects, neural tube defects can be preventable. Here’s what you should know about neural tube defects if you’re pregnant and steps you can take for a healthy pregnancy.
What are neural tube defects?
Neural tube defects are major birth defects that can affect the:
Brain
Skull
Spinal cord
Spine
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The neural tube is a structure that forms in early pregnancy. It eventually matures into the central nervous system, which includes the brain and spinal cord. If the neural tube doesn’t form properly, then the central nervous system won’t form properly either. Neural tube defects lead to conditions like:
Anencephaly
Encephalocele
Iniencephaly
Lipomyelomeningocele or lipomeningocele
There’s no cure for these conditions. Some of them can lead to death. The fetus may not survive until birth or may not live very long after they’re born.
Some of these conditions, like spina bifida, are not lethal. But even in these cases, children usually have lifelong health issues related to their condition. For example, children with spina bifida may have trouble walking or controlling their bowel and bladder.
When do neural tube defects develop during pregnancy?
The neural tube starts forming during the third week of pregnancy. It finishes forming (or “closes”) by day 28 to 32 of pregnancy. Neural tube defects develop between these two periods.
Keep in mind that these weeks of development correspond to the fifth to seventh week of pregnancy. So neural tube defects develop very early in a pregnancy. In fact, many people don’t even know they’re pregnant yet.
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What causes neural tube defects?
A combination of factors causes neural tube defects. Researchers are still investigating how these factors come together to trigger a neural tube defect.
Exposures to certain infections, medications, alcohol, and chemicals during early pregnancy can increase the chance of a neural tube defect. People who have certain medical conditions, like diabetes, are also more likely to have a pregnancy affected by a neural tube defect.
Genetics also play a role. You’re more likely to have a pregnancy with a neural tube defect if you had a previous pregnancy with a neural tube defect. Neural tube defects also run in families. So if you have a parent, sibling, or spouse with a neural tube defect, you’re more likely to have a pregnancy affected by a neural tube defect.
Can you prevent neural tube defects?
There are steps you can take to lower the risk of a neural tube defect.
1. Take folic acid supplements
Taking a folic acid supplement is the most important thing you can do to lower the risk of a neural tube defect.
Folic acid supplements lower the risk of a neural tube defect by up to 70%. Folic acid (vitamin B9) lets the fetus make the DNA it needs for proper growth and development.
When you’re not pregnant, you can get enough folic acid from your regular diet. But, when you’re pregnant, diet alone won’t provide enough folic acid to meet your body’s needs plus the needs of a growing fetus.
Experts recommend taking an additional 400 mcg to 800 mcg of folic acid each day if you’re pregnant or planning to become pregnant. The American College of Obstetrics and Gynecology (ACOG) recommends taking 600 mcg of folic acid every day starting 1 month before pregnancy through the first trimester of pregnancy.
Notice that experts recommend starting folic acid supplements even before you become pregnant. That’s because the neural tube forms even before many people know they’re pregnant. If you find out you’re pregnant after the neural tube closes (when you’re about 6 weeks along), it’s too late to get the benefits from folic acid.
You can get enough folic acid by taking a daily vitamin and eating foods with folic acid. Prenatal vitamins contain at least 400 mcg of folic acid. Many daily multivitamins contain folic acid, too. But check the label because they may not contain enough folic acid to meet the daily goal of 400 mcg to 800 mcg.
You need to take more folic acid if you had a previous pregnancy affected by a neural tube defect. Experts recommend that you take 4,000 mcg of folic acid each day starting 1 month before you get pregnant. You should continue taking these supplements until at least the end of your first trimester. Your genetic counselor may have additional recommendations on how much folic acid you should take.
2. Optimize your health
Certain medical conditions and medications increase the risk of a neural tube defect. If you have diabetes or obesity, you have a higher chance of having a pregnancy affected by a neural tube defect. Work with your healthcare team to optimize your treatment plans. This can lower your risk of a neural tube defect.
Medications that increase the risk of a neural tube defect include:
Valproic acid
Carbamazepine
Vitamin A
Sulfamethoxazole-trimethoprim
Sulfasalazine
Azathioprine
Some antacids
Rifampicin
Talk with your healthcare team if you take one or more of these medications. You may be able to change to a safer alternative. If you’re thinking about getting pregnant, have this conversation before you start trying to get pregnant.
Don’t stop taking your medications without talking with your healthcare team. This can lead to serious health issues that can harm you and your developing fetus.
3. Avoid overheating
Overheating has been linked to an increased risk of a neural tube defect. Avoid hot tubs, steam rooms, saunas, and hot baths during early pregnancy and while trying to become pregnant. You also want to avoid extremely hot weather when possible.
See your healthcare team if you get sick and develop a fever. Fever can increase your risk of overheating. Your team can tell you how to safely treat a fever during pregnancy. Some over-the-counter fever relievers are not safe to take during pregnancy.
Can you detect neural tube defects during pregnancy?
Yes. Neural tube defects can be diagnosed during pregnancy.
Experts recommend getting screening blood tests during the second trimester. As part of this test, you’ll have your maternal serum alpha fetoprotein (aFP) measured. AFPs are higher when there is a neural tube defect. Prenatal ultrasounds can show signs of neural tube defects.
AFP testing and prenatal ultrasounds are screening tests for neural tube defects. If they show a concern, you may need specific testing. This can include a fetal MRI or CT scan. Sometimes, people also need an amniocentesis to help diagnose a neural tube defect. This test collects a small sample of the fluid surrounding the fetus. The fluid can then be checked for markers of neural tube defects.
The bottom line
Neural tube defects are birth defects that affect the brain and spinal cord. The defect develops very early on in a pregnancy, often before people realize they are pregnant. You can lower your risk of a neural tube defect by taking a daily folic acid supplement. You need at least 400 mcg of folic acid each day during the first trimester of pregnancy.
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References
American College of Obstetricians and Gynecologists. (2023). Nutrition during pregnancy.
Avagliano, L., et al. (2019). Overview on neural tube defects: From development to physical characteristics. Birth Defects Research.
Centers for Disease Control and Prevention. (2023). Facts about neural tube defects.
Centers for Disease Control and Prevention. (2023). Folic acid recommendations.
Centers for Disease Control and Prevention. (2023). 5 ways to lower the risk of having a pregnancy affected by a neural tube defect.
Kondo, A., et al. (2017). Neural tube defects: Risk factors and preventive measures. Congenital Anomalies.
March of Dimes. (2022). Neural tube defects.
MedlinePlus. (2016). Neural tube defects.
National Institute of Child Health and Human Development. (2017). How do health care providers diagnose neural tube defects (NTDs)?
New York State Department of Health. (2007). Folic acid: The vitamin that helps prevent birth defects.
University of Rochester Medical Center. (n.d.). Open neural tube defects (ONTDs) in children.
U.S. Food and Drug Administration. (2022). FDA recommends avoiding use of NSAIDs in pregnancy at 20 weeks or later because they can result in low amniotic fluid.
U.S. Preventive Services Task Force. (2023). Folic acid supplementation to prevent neural tube defects: Preventive medication.
