Spina bifida is a birth defect where the spine doesn’t close completely during early pregnancy, leaving a gap in the vertebrae that can expose or damage the spinal cord. About 1,278 babies are born with it each year in the United States, roughly 1 in every 2,875 births. The condition ranges from so mild that a person never knows they have it to severe enough to cause paralysis and lifelong health challenges.
The Three Types of Spina Bifida
Not all spina bifida is the same. The three types differ based on whether the spinal cord is affected and how much damage occurs.
Spina bifida occulta is the mildest form. There’s a small gap in the spine, but no opening on the back and no fluid-filled sac. The spinal cord and nerves are typically normal, and most people with this type have no symptoms or disabilities. Many never find out they have it unless an X-ray or scan happens to reveal it.
Meningocele involves a sac of fluid that pushes through an opening in the back, but the spinal cord itself stays in place. Because the nerves are usually undamaged, this type tends to cause only minor disabilities.
Myelomeningocele is the most serious form. A fluid-filled sac protrudes from the back, and part of the spinal cord and nerves are inside it, where they sustain damage. This type causes moderate to severe disabilities, often including inability to move the legs, and requires surgical repair shortly after birth.
What Causes It
Spina bifida develops in the first few weeks of pregnancy, often before a person even knows they’re pregnant. The neural tube, which eventually becomes the brain and spinal cord, fails to close properly. The exact cause is a combination of genetic and nutritional factors.
One well-studied genetic contributor is a variation in a gene that helps the body process folate, a B vitamin essential for neural tube development. People who carry two copies of this variant have roughly 2.5 times the usual risk of having a child with a neural tube defect. Those with one copy still face about 1.5 times the risk. Together, these variants account for an estimated 26% of neural tube defects in some populations. The good news: even in people with these genetic variants, taking folic acid corrects the underlying folate and homocysteine imbalances that drive the risk.
Other risk factors include obesity, poorly controlled diabetes, certain anti-seizure medications, and higher body temperatures in early pregnancy from fever or hot tub use.
How Folic Acid Prevents It
Folate deficiency is involved in an estimated 50% to 70% of neural tube defects, making folic acid supplementation the single most effective prevention strategy. The CDC recommends that all women capable of becoming pregnant take 400 micrograms of folic acid daily. Women who have already had a pregnancy affected by a neural tube defect are advised to take 4,000 micrograms daily if they plan to become pregnant again. Because the neural tube closes so early in pregnancy, waiting until a positive pregnancy test is often too late.
Prenatal Diagnosis
Spina bifida is typically detected during routine prenatal screening. A blood test in the second trimester can flag elevated levels of a protein that suggests an open neural tube defect, and a detailed ultrasound can then confirm the diagnosis.
On ultrasound, open spina bifida produces characteristic changes in the baby’s skull shape. A “lemon sign,” where the frontal bones appear pinched inward, is present in 98% of affected fetuses before 24 weeks of pregnancy. Abnormalities in the cerebellum (the lower part of the brain) are visible in about 95% of cases regardless of gestational age. These markers, combined with direct visualization of the spinal defect, make ultrasound highly accurate for diagnosis.
Surgical Treatment Before and After Birth
Myelomeningocele requires surgical closure to protect the exposed spinal cord. This surgery can happen either before birth (while the baby is still in the womb) or within the first day or two after delivery.
Prenatal surgery, performed during the second trimester, has become an increasingly available option. Candidates for fetal repair need to meet specific criteria: the baby must show hindbrain herniation on imaging, the spinal lesion must fall between certain vertebral levels, and there should be no other major anatomical or genetic abnormalities that would limit the benefit. Babies who undergo prenatal repair need fewer shunts to drain excess fluid from the brain, which is one of the procedure’s major advantages. Many children who have prenatal surgery can also be treated with a less invasive procedure if fluid buildup does occur later, rather than needing a permanent shunt.
Postnatal surgery, performed within 24 to 48 hours of birth, remains the standard approach when prenatal surgery isn’t possible. The surgeon closes the opening, tucks the spinal cord back into place, and covers it with tissue and skin.
Walking Ability Depends on Lesion Level
One of the first questions parents ask is whether their child will walk. The answer depends heavily on where on the spine the defect is located. Lower lesions leave more nerve function intact, which means better mobility.
Children with sacral-level lesions (the lowest part of the spine) have the best outlook. In a long-term study from the Royal Children’s Hospital in Melbourne, all 68 children with sacral lesions walked, starting at an average age of about 2 years and 2 months. None had stopped walking by the end of the study.
At the low-lumbar level (around L4/L5), 84% of children walked, starting around age 3 years and 10 months, though a small number stopped walking by about age 9. At the mid-lumbar level (L3), 60% walked, starting around age 5. For thoracic-level lesions, the highest and most severe, only 20% achieved community walking, and most of those stopped within a few years.
Even children with the lowest lesions experience some delay in learning to walk compared to children without spina bifida. Braces, walkers, and physical therapy play a major role in helping children reach their mobility potential, and many people with higher-level lesions use wheelchairs as their primary means of getting around.
Chiari II Malformation
Nearly all children born with myelomeningocele also develop a related brain condition called Chiari II malformation. The open spinal defect changes pressure dynamics in the developing brain, causing the lower part of the brain to shift downward through the opening at the base of the skull. This crowding can compress the brainstem, which controls breathing, swallowing, and heart rate.
In infants, this compression can cause breathing pauses, a high-pitched breathing sound called stridor, and feeding difficulties like choking, nasal regurgitation, or very slow feeding. Most children with Chiari II malformation are monitored closely but don’t need treatment unless these symptoms become severe. When they do, surgical decompression to relieve pressure at the base of the skull is sometimes necessary. Infants who develop vocal cord paralysis, arm weakness, or cardiopulmonary problems that come on rapidly have a much more serious prognosis than those whose symptoms develop gradually.
Bladder and Bowel Management
The nerves that control the bladder and bowel run through the lower spine, so most people with myelomeningocele have some degree of bladder and bowel dysfunction. Managing these functions is one of the most important parts of daily life with spina bifida.
For the bladder, clean intermittent catheterization is the cornerstone of care. This means passing a thin tube through the urethra to empty the bladder on a regular schedule, typically every few hours. Most children learn to do this independently as they get older. Some children also need medication to relax an overactive bladder, and in more complex cases, surgery can improve bladder capacity or create a more accessible opening for catheterization, which is especially helpful for people who use wheelchairs.
Bowel management usually involves a scheduled enema routine, often started around age 3. Most children do well with a rectal enema using tap water, which trains the colon to empty predictably. For the small number who don’t respond to this approach, a minor surgical procedure can create an opening that allows enemas to be delivered from the top of the colon instead, which tends to be more effective.
Health Concerns in Adulthood
Spina bifida is a lifelong condition, and adults face a unique set of health challenges that require ongoing attention. Kidney function is a primary concern because years of abnormal bladder pressure can gradually damage the kidneys. Regular monitoring helps catch problems before they become serious.
Latex allergy is unusually common in people with spina bifida, likely because of repeated exposure to latex-containing medical supplies from an early age. This allergy can cause reactions ranging from skin irritation to life-threatening anaphylaxis. Latex is still found in many everyday environments, including hospitals, schools, and community facilities. People with spina bifida and a known latex allergy need to carry self-injectable epinephrine and keep their prescriptions current.
Skin breakdown is another persistent risk, particularly for wheelchair users who may not feel pressure on their skin. Tethered spinal cord, where scar tissue anchors the spinal cord and causes new neurological symptoms as a person grows, can occur at any age and sometimes requires additional surgery. Obesity, depression, and social isolation also affect adults with spina bifida at higher rates, making access to coordinated adult healthcare especially important.