What Are Neural Tube Defects?

In the earliest weeks of pregnancy, a structure called the neural tube forms and eventually becomes the brain and spinal cord. It usually seals shut by day 28 after conception, often before a woman has even gotten a positive pregnancy test. When that closing process goes wrong, the result is a neural tube defect.

In the United States, neural tube defects affect roughly 1 in 1,000 pregnancies. They rank among the most common structural birth defects, and among the most preventable.

Types of Neural Tube Defects

Spina Bifida

Spina bifida happens when the spinal portion of the neural tube fails to close fully. It comes in several forms, from very mild to quite significant:

  • Spina bifida occulta: The mildest form. A tiny gap remains in the spine, but the spinal cord and nerves are usually left alone. Most people with occulta never find out they have it; it tends to show up by accident on an X-ray done for something else entirely.
  • Meningocele: The protective membranes around the spinal cord, called meninges, bulge through the gap in the spine and form a fluid-filled sac. The spinal cord itself typically stays put, and surgical repair usually goes well.
  • Myelomeningocele: The most serious form. The spinal canal stays open across several vertebrae, and part of the spinal cord and nerves pushes through the opening. This can affect mobility, bladder and bowel control, and in some cases cognitive development, depending on where and how large the opening is.

Anencephaly

Anencephaly occurs when the upper end of the neural tube fails to close, so the brain and skull do not develop fully. It is a condition that is incompatible with life outside the womb. Most of these pregnancies end in stillbirth, and babies born alive generally survive only hours to days. Receiving this diagnosis is devastating, and families deserve compassionate, individualized support as they work through their options.

Prevention: The Power of Folate

Folate, also known as vitamin B9, is the single most effective tool we have for preventing neural tube defects. Studies consistently show that getting enough folate before conception and during those first weeks of pregnancy cuts the risk by 50% to 70%.

How Much and When

  • The recommended daily intake is 400 micrograms (mcg) of folic acid for anyone who could become pregnant
  • People with a previous NTD-affected pregnancy, certain medications (such as anti-seizure drugs), or specific genetic variants may be advised to take 4,000 mcg (4 mg) daily, beginning at least one month before conception
  • Because the neural tube closes so early, starting supplementation before pregnancy is ideal. By the time most people realize they are pregnant, that critical window may already be over

Food Sources

Folate occurs naturally in:

  • Dark leafy greens (spinach, kale, romaine)
  • Legumes (lentils, black beans, chickpeas)
  • Asparagus, broccoli, and Brussels sprouts
  • Citrus fruits and avocado

In the United States, enriched grain products like bread, cereal, and pasta are required by federal mandate to be fortified with folic acid. That policy, put in place in 1998, lowered NTD rates by about 28%.

Even if your diet is rich in folate, a daily prenatal vitamin with folic acid gives you a reliable safety net.

How Neural Tube Defects Are Detected

Blood Screening

The maternal serum alpha-fetoprotein (AFP) test, usually drawn between 15 and 20 weeks, measures a protein made by the fetal liver. High AFP levels can point toward a neural tube defect, though false positives happen. An elevated result means more testing is needed, not an immediate diagnosis.

Anatomy Scan

The anatomy ultrasound at 18 to 22 weeks can pick up spinal abnormalities and certain cranial markers linked to NTDs. Improved imaging technology has made prenatal detection considerably more reliable over the past couple of decades.

Amniocentesis

When screening raises concerns, amniocentesis can measure AFP and acetylcholinesterase levels in the amniotic fluid, offering a more definitive answer.

Treatment: What Is Possible Today

Fetal Surgery for Myelomeningocele

One of the biggest advances in treating neural tube defects is fetal surgery. The landmark MOMS (Management of Myelomeningocele Study) trial showed that repairing myelomeningocele before birth, typically around 23 to 26 weeks of pregnancy, can reduce the need for a shunt to manage fluid buildup in the brain and improve motor outcomes compared with repairing after delivery.

Fetal surgery is not right for every case, and it carries its own risks, including preterm birth. It is performed at specialized centers by highly trained teams. If your baby is diagnosed with myelomeningocele, a referral to a fetal surgery center for evaluation can help you understand whether this option is available to you.

Postnatal Care

Babies born with myelomeningocele generally have the opening surgically closed within the first few days of life. Ongoing care often includes:

  • Physical and occupational therapy
  • Urology and bowel management support
  • Orthopedic monitoring
  • Neurosurgical follow-up if a shunt is placed

Many people with spina bifida live rich, full, and active lives. Advances in surgical technique, rehabilitation, and assistive technology keep improving outcomes and independence.

Finding Prenatal Care on BAABY

If you are navigating a neural tube defect diagnosis or want to make sure your prenatal care includes the right screening and supplementation guidance, BAABY's provider directory can help you find OB-GYNs and maternal-fetal medicine specialists in your area who can offer expert, compassionate support.