Spina bifida is a birth defect in which part of the spinal column fails to close during early embryonic development, leaving a gap that can expose or damage the spinal cord and surrounding nerves. It ranges from a small, hidden bone defect that may never cause symptoms to a severe open lesion that affects movement, bladder function, and brain development. The condition arises during the first few weeks of pregnancy, often before a woman knows she is pregnant, and its severity depends largely on the location and size of the opening along the spine.
How the Defect Forms
During the third and fourth weeks after conception, the embryo forms a flat strip of tissue called the neural plate, which normally folds inward and closes into a tube that eventually becomes the brain and spinal cord. When part of this tube fails to close, an opening remains. The type of spina bifida that results depends on where along the spine the closure failed and how much tissue is exposed.
Open neural tube defects, including the most common severe form called myelomeningocele, result from failure of this closure process in the lower back region.1PubMed Central. Neural tube defects–disorders of neurulation and related embryonic processes The specific part of the spine affected shapes the resulting disability, because the nerves that exit at different levels control different muscles and organs.2PubMed Central. Genetics and development of neural tube defects A defect at the lower lumbar level might spare some leg function, while one higher up can affect the legs, hips, bladder, and bowel more broadly.
Types of Spina Bifida
Spina bifida is not a single condition but a spectrum. The types differ dramatically in how they affect daily life.
- Spina bifida occulta: The mildest form, where one or more vertebrae have a small gap but the spinal cord and its coverings remain inside. Many people have this and never know it. A small dimple, patch of hair, or birthmark on the lower back may be the only clue. It rarely causes neurological problems.
- Meningocele: The protective membranes around the spinal cord push out through the gap in the spine, forming a fluid-filled sac visible on the baby’s back. The spinal cord itself stays in place, so neurological damage tends to be mild. This form is uncommon.
- Myelomeningocele: The most clinically significant form. The spinal cord and nerves push through the opening along with the membranes, often leaving neural tissue exposed. This causes moderate to severe nerve damage below the level of the defect.3PubMed Central. Spina bifida
- Myeloschisis: A particularly severe variant in which the neural plate lies completely open and flat, with no covering at all. In one systematic review of 90 cases, myeloschisis was the most frequent subtype, found in about a third of cases.4Oxford Academic. Systematic Classification of Spina Bifida
When clinicians refer to “spina bifida” without further qualification, they usually mean myelomeningocele, because it accounts for the bulk of serious cases and drives the lifelong medical management the condition requires.
What Raises the Risk
Spina bifida results from a tangle of genetic susceptibility and environmental factors. No single gene causes it, and no single exposure guarantees it. But several contributors are well established.
Folate deficiency is the strongest modifiable risk factor. The B vitamin folate is essential for normal neural tube closure, and women who do not get enough of it around the time of conception face a significantly higher chance of having an affected pregnancy. After the United States mandated folic acid fortification of enriched grain products in 1998, the estimated number of babies born each year with spina bifida dropped by roughly 770, saving an estimated $603 million in direct medical costs per birth cohort.5PubMed Central. Retrospective Assessment of Cost Savings From Prevention: Folic Acid Fortification and Spina Bifida in the U.S.
Genetics also plays a role, particularly variants in the gene for an enzyme called MTHFR that helps the body use folate. In one early study, the variant was found in about 16 percent of mothers of children with spina bifida, compared with 5 percent of controls.6PubMed. Mutated methylenetetrahydrofolate reductase as a risk factor for spina bifida A larger gene-interaction study estimated that carrying two copies of this variant raised the odds of spina bifida by about 50 percent.7Genetics in Medicine. Spina bifida and folate-related genes: A study of gene-gene interactions The variant impairs folate metabolism and raises blood levels of homocysteine, a compound linked to developmental problems.
Maternal diabetes is another major factor. A Canadian study found that women with type 2 diabetes had nearly four times the rate of spina bifida compared with women without diabetes.8PubMed. Association of maternal risk factors with the recent rise of neural tube defects in Canada A separate analysis found that the combined effect of diabetes and low folic acid intake was considerably worse than either factor alone, with roughly quadrupled odds of spina bifida when both were present.9American Journal of Obstetrics and Gynecology. The impact of folic acid intake on the association among diabetes mellitus, obesity, and spina bifida Additional risk factors identified in research include certain maternal infections, drug exposures during early pregnancy, and substance use.10PubMed. Periconceptional risk factors of spina bifida among Egyptian population: a case-control study
How Spina Bifida Is Detected Before Birth
Most cases of open spina bifida are now picked up on prenatal ultrasound, often during the routine anatomy scan around 18 to 20 weeks of pregnancy. The ultrasound can show characteristic skull and brain changes caused by the open spine, as well as the spinal defect itself. Studies using these “cranial signs” report sensitivities above 90 percent, meaning the scan catches the vast majority of cases.11PubMed. Cost-benefit analysis of targeted ultrasonography for prenatal detection of spina bifida in patients with an elevated concentration of second-trimester maternal serum alpha-fetoprotein
A maternal blood test measuring alpha-fetoprotein, a protein that leaks into the mother’s blood when the fetal skin is open, has traditionally been used as a screening tool. But this test alone misses a meaningful share of spina bifida cases. In one large review, blood screening failed to flag about 38 percent of spina bifida cases, meaning more than a third would have gone undetected without an ultrasound.12Obstetrics & Gynecology. Routine Ultrasonography Compared With Maternal Serum Alpha-fetoprotein for Neural Tube Defect Screening Most prenatal centers now rely primarily on ultrasound, sometimes supplemented by blood testing or amniocentesis when the picture is unclear.
Prenatal Versus Postnatal Surgery
Open myelomeningocele requires surgical closure to protect the exposed spinal cord. Historically, this was done within a day or two after birth. But a landmark trial changed the conversation by showing that operating on the fetus before birth could improve certain outcomes.
In that trial of 158 pregnancies, prenatal surgery cut the rate of shunt placement for hydrocephalus roughly in half compared with postnatal repair, with actual shunt placement rates of about 40 percent versus 82 percent. Prenatal surgery also improved motor function and reduced hindbrain herniation, a brain abnormality common in myelomeningocele.13PubMed Central. A randomized trial of prenatal versus postnatal repair of myelomeningocele These are substantial benefits for the child.
The trade-off is risk to the mother and the pregnancy. Prenatal surgery was associated with babies arriving about three weeks earlier on average, a fivefold increase in preterm birth before 37 weeks, and a sixfold increase in premature rupture of the membranes.14PubMed Central. Prenatal versus postnatal repair procedures for spina bifida for improving infant and maternal outcomes The mother must deliver by cesarean section, and the uterine scar from fetal surgery requires cesarean delivery for future pregnancies as well. This means the decision is genuinely complex and depends on the specific case, the gestational age at diagnosis, and the family’s access to a specialized fetal surgery center.
Hydrocephalus and the Chiari II Malformation
The majority of babies born with myelomeningocele develop hydrocephalus, a buildup of fluid in the brain’s ventricles. The reason is mechanical: while the spine is open in utero, spinal fluid leaks out instead of circulating normally through the developing brain. This fluid loss causes the rear part of the brain to shift downward into the spinal canal, a structural abnormality called the Chiari II malformation.15PubMed. The Chiari II malformation: cause and impact After the spine is closed at birth, the fluid can no longer escape, and it accumulates.
Most children who develop hydrocephalus need a surgically placed shunt, a tube that drains excess fluid from the brain into the abdomen. Shunts work well but are prone to blockages and infections over a lifetime, often requiring multiple revision surgeries. An alternative approach combines a procedure that creates a new drainage pathway inside the brain with cauterization of the tissue that produces the fluid. In a study of 115 infants, this combined approach appeared to provide more durable results than shunts and may be especially useful in settings where shunt maintenance is difficult.16PubMed. Combined endoscopic third ventriculostomy and choroid plexus cauterization as primary treatment of hydrocephalus for infants with myelomeningocele
Bladder and Bowel Management
Almost everyone born with myelomeningocele has some degree of bladder and bowel dysfunction, because the nerves controlling these functions exit the lower spine, precisely where the defect occurs. Left unmanaged, a poorly functioning bladder can cause repeated urinary tract infections and, over time, permanent kidney damage. Protecting the kidneys is the top priority of urological care in spina bifida.17PubMed. Urologic management of spina bifida
The standard approach begins at birth with clean intermittent catheterization, where a thin tube is inserted into the bladder on a schedule to drain urine, combined with medications to relax the bladder muscle. Starting early is critical because the bladder can start damaging the kidneys in the first months of life.18PubMed Central. Treatment of the neurogenic bladder in spina bifida With consistent management, the majority of children can be dry by the time they start school. Existing studies generally favor this proactive strategy over a wait-and-see approach, though specific protocols vary between centers.19PubMed. Medical management of neurogenic bladder in patients with spina bifida: A scoping review
Bowel management follows a similar logic. Many individuals use a program of timed toileting, dietary adjustments, and sometimes rectal irrigations. For those who cannot achieve reliable continence with conservative methods, a surgical procedure called a MACE creates a channel from the skin surface to the colon through which a flush of fluid can be instilled, essentially washing the bowel on a schedule. Long-term follow-up shows that most people with spina bifida who receive this procedure continue using it into adulthood, with only about one percent stopping per year.20PubMed. People with spina bifida use their MACE on long-term follow-up: A single institutional retrospective cohort study Satisfaction rates are high, particularly among those who had the procedure at a younger age.21Spinal Cord. Satisfaction after the Malone antegrade continence enema procedure in patients with spina bifida
Mobility and Orthopedic Concerns
How well someone with spina bifida walks depends almost entirely on the neurological level of the defect. Children whose functioning nerve level is at the sacral segments, near the bottom of the spine, often walk independently with minimal bracing. Those with defects at the upper lumbar level may need long leg braces, crutches, or a wheelchair for longer distances. Three-dimensional gait analysis confirms what clinicians observe: children with higher-level defects show greater deviations in hip and pelvic motion compared with those whose defect is lower.22Journal of Pediatric Orthopaedics B. Gait profile score and gait variable scores in spina bifida
Orthopedic issues are common throughout childhood and into adulthood. Muscle imbalances from uneven nerve damage can pull joints out of alignment, leading to foot deformities, hip dislocations, and scoliosis. Fractures in the legs are more frequent than in the general population because bones that bear less weight become thinner and more fragile. Children and adults with spina bifida often work with orthopedic surgeons and physical therapists throughout life to maintain the best possible function.
Tethered Cord Syndrome
After the initial spinal repair, scar tissue can anchor the spinal cord to the surrounding structures, preventing it from moving freely within the spinal canal as the child grows. This is called tethered cord syndrome, and it can appear years after the original surgery. Symptoms often develop gradually and can include worsening leg weakness, new pain, changes in gait, and declining bladder function.23PubMed Central. Late-Onset Tethered Cord Syndrome in a Patient with Spina Bifida: A Case Report
Surgery to release the tethered cord can help, but the results are mixed and depend on the symptom. In a study of 112 patients followed for an average of nearly 14 years, pain improved most often, with remission in about 30 percent of cases, while bladder dysfunction improved in only about 13 percent. A sobering finding was that roughly a quarter to 40 percent of patients experienced some deterioration during long-term follow-up even after surgery, and those who needed a second operation saw even lower rates of improvement.24PubMed. Clinical Outcomes of Primary and Revision Untethering Surgery in Patients with Tethered Cord Syndrome and Spinal Bifida This underscores why ongoing neurological monitoring is a permanent part of spina bifida care.
Why Latex Allergy Is a Serious Concern
People with spina bifida are far more likely to develop allergies to natural rubber latex than the general population. One study found that about 40 percent of spina bifida patients had latex-specific antibodies, compared with roughly 2 percent of healthy controls.25PubMed. Natural rubber latex allergy: prevalence and risk factors in patients with spina bifida compared with atopic children and controls The risk climbs with each surgery, because repeated exposure to latex gloves and medical equipment during operations appears to prime the immune system.26The Journal of Immunology. Characterization of T Cell Responses to Hev b 3, an Allergen Associated with Latex Allergy in Spina Bifida Patients
Reactions can range from skin rashes to life-threatening anaphylaxis. Because of this, clinical guidelines now recommend that all medical procedures on individuals with spina bifida be performed in a latex-free environment from birth onward.27PubMed Central. Latex allergy guidelines for people with spina bifida Parents are generally advised to avoid latex products at home as well, including certain balloons, rubber bands, and toys.
Cognitive and Social Effects
Spina bifida is often thought of as a purely physical condition, but the brain is affected too, especially in people who have hydrocephalus. On average, people with spina bifida score lower on intelligence testing than their peers without the condition, though the range is wide and many individuals have intellectual abilities in the normal range. Beyond IQ scores, difficulties with attention, memory, planning, and organization are common and often more disabling in daily life than the cognitive scores alone suggest.28PubMed Central. A scoping review of cognition in spina bifida and its consequences for activity and participation throughout life
These challenges have real downstream effects. Adolescents with spina bifida show clear impairments in attention and executive functioning even after controlling for overall intelligence, and these cognitive difficulties help explain the social adjustment problems many experience, including trouble making and keeping friends.29Journal of Pediatric Psychology. Attention and Executive Functions in Adolescents with Spina Bifida Cognitive difficulties can also make it harder for adults to manage their own medical care independently, since catheterization schedules, medication regimens, and symptom monitoring all require executive function skills.
Growing Up and Transitioning to Adult Care
The shift from pediatric to adult healthcare is one of the most vulnerable periods for people with spina bifida. As a historically lethal condition that only became survivable in the mid-twentieth century with the advent of antibiotics and modern shunts, adult medical systems are still catching up.30PubMed Central. Living with spina bifida: a historical perspective Many adult physicians have little training in the condition, and the coordinated multidisciplinary clinics common in pediatric care are rarer for adults.
A survey of U.S. spina bifida transitional care practices found that most clinics consistently address mobility, bladder and bowel management, and transportation needs. But important topics like sexuality, pregnancy, and reproductive health come up far less often, even though these are central concerns for young adults.31PubMed Central. Evaluation of spina bifida transitional care practices in the United States Weight management, while discussed in most clinics, is a growing concern because reduced mobility makes it easier to gain weight, which in turn worsens skin breakdown, joint stress, and cardiovascular risk.
Regenerative Medicine and What Comes Next
Current surgical repair, whether before or after birth, essentially closes the opening and protects the spinal cord from further damage. It does not restore nerve function that has already been lost. That limitation has driven interest in regenerative approaches that aim to repair rather than simply cover the defect. Researchers are now exploring strategies that combine stem cells, bioengineered scaffolds, and cell-derived products with fetal surgery to promote actual neural tissue repair.32PubMed Central. Advances in Fetal Repair of Spina Bifida Integrating Prenatal Surgery, Stem Cells, and Biomaterials These are still in early experimental stages, tested primarily in animal models, and it will be years before they are available clinically. But the shift from thinking about spina bifida surgery as a “patch job” toward thinking about it as a platform for regeneration represents a meaningful change in the field’s ambition. For families receiving a diagnosis today, the practical reality remains managing the condition with the tools that already exist, but the long-term trajectory of the science looks more hopeful than at any point in the past.