The symptoms and medical signs of spina bifida can range from very mild to severe, depending on the type of spina bifida and the level of the spine that is affected. In moderate to severe cases (like the myelomeningocele form), there is an obvious opening or sac on the newborn’s back at birth. This can lead to partial or complete paralysis of the body below the level of the spinal opening (MedlinePlus Genetics, n.d.). Babies with severe spina bifida often cannot move or feel their legs. They often have trouble with bladder and bowel control as the nerves that supply the bladder and intestines may be impaired. Other issues can accompany spina bifida as well, such as hydrocephalus, which is a buildup of excess fluid in the brain (MedlinePlus Genetics, n.d.). Hydrocephalus occurs in a significant number of children with myelomeningocele and, if untreated, can cause headaches, developmental delay, or vision problems; it is usually managed with a shunt (a tube to drain fluid). Some individuals with spina bifida, particularly those with hydrocephalus, may have learning difficulties or cognitive challenges (MedlinePlus Genetics, n.d.), though many have normal intelligence. There can also be orthopedic problems like clubfoot, hip dislocations, or scoliosis due to weakened spinal and leg muscles. Additionally, because of nerve damage and reduced sensation, skin wounds on the legs/feet may go unnoticed and become serious.

Milder cases of spina bifida may have very subtle or no symptoms. In spina bifida occulta, often referred to as “hidden” spina bifida, the spinal cord and nerves are typically normal and remain inside the spinal column. Most people with occulta have no neurological problems. In many instances, the person is unaware of the condition until an X-ray or scan (done for an unrelated reason) incidentally reveals it (CDC, 2024b). Externally, occulta sometimes causes a small birthmark, dimple, or patch of hair on the lower back above the affected area (UCSF Benioff Children's Hospitals, n.d.). These minor skin signs might prompt a doctor to investigate further with imaging. Because the nerves are unharmed in occulta, it usually does not cause disability – though rarely it can be associated with back pain or minor bladder issues (UCSF Benioff Children's Hospitals, n.d.).

Spina bifida can be diagnosed before birth (prenatally) or after the baby is born. Today, prenatal screening is a routine part of pregnancy care and often detects moderate to severe spina bifida. One common screening test is the maternal serum alpha-fetoprotein (AFP) test, performed between about 15 and 20 weeks of pregnancy (UCSF Benioff Children's Hospitals, n.d.). AFP is a protein produced by the fetus. If a fetus has an open spina bifida, AFP can leak from the spinal opening into the amniotic fluid and then into the mother’s blood at higher-than-normal levels. An unusually high AFP level in the mother’s blood can indicate a possible spina bifida—or other neural tube defect (CDC, 2024b). It’s important to note this is a screening test, not a confirmation. If a high AFP or other markers are found, doctors will usually recommend further testing. The most useful test is an ultrasound exam, which uses sound waves to create an image of the developing baby. A detailed ultrasound can often visualize the spine and detect an opening or sac on the fetus’s back (CDC, 2024b). Ultrasound can also sometimes show secondary signs like certain changes in the baby’s head shape that are associated with spina bifida. In some cases, an amniocentesis might be offered: this is a procedure where a small sample of the amniotic fluid is taken with a needle. In spina bifida, amniotic fluid AFP is typically elevated, and amniocentesis can also detect changes in other substances (like acetylcholinesterase) that support the diagnosis (UCSF Benioff Children's Hospitals, n.d.). If spina bifida is confirmed during pregnancy, families will usually meet with a specialized team (including a maternal-fetal medicine doctor, pediatric neurosurgeon, and often a genetic counselor) to discuss treatment options and prepare for the baby’s needs.

When spina bifida is not diagnosed prenatally, it is often identified at birth by visual exam if a newborn has the characteristic sac or lesion on the back. The medical team will typically perform imaging, such as an X-ray, ultrasound, or MRI of the spine, to confirm the diagnosis and see the extent of the defect (CDC, 2024b). Mild cases like occulta can be so subtle that they may go undetected in infancy. In occulta, sometimes a tuft of hair or dimple on the lower back is the only clue (CDC, 2024b). If a doctor sees such signs, they may have an imaging study of the infant’s spine to check for an underlying defect. Some individuals don’t discover they have spina bifida occulta until adolescence or adulthood when a back X-ray is done for another reason.

Families who receive a prenatal diagnosis of spina bifida are typically offered genetic counseling as part of their care. A genetic counselor can help explain the condition, what to expect, and the results of any genetic tests. They also discuss the chances of spina bifida occurring in future pregnancies and how to potentially reduce that risk. If a couple has had one child with a neural tube defect like spina bifida, genetic counseling is recommended before another pregnancy (Spina Bifida Association, n.d.). The counselor will review any family history of birth defects and advise genetic testing to rule out rare syndromes. Counselors also guide families through decisions about prenatal interventions (for example, whether to pursue fetal surgery—discussed later—or plan for delivery at a specialized hospital). In summary, genetic counseling is a valuable part of the support system, helping families navigate various aspects of a spina bifida diagnosis.

Spina bifida is considered a multifactorial condition, meaning it results from a combination of genetic predispositions and environmental influences. There is no single gene that “causes” spina bifida in most cases. Instead, multiple genes can contribute to a person’s susceptibility, and various external factors can trigger or prevent the defect during pregnancy (MedlinePlus Genetics, n.d.). Most infants with spina bifida are born to parents with no family history of the condition. However, having one child with spina bifida modestly increases the risk for subsequent children—on the order of a few percent (MedlinePlus Genetics, n.d.), and spina bifida is slightly more likely in babies who have an affected sibling or parent compared to those who do not. This pattern suggests that inherited genetic factors are involved, but it’s not a dominant or recessive single-gene inheritance. Instead, it is complex inheritance.

A number of risk factors have been identified that increase the chance of spina bifida in a pregnancy:

• • Inadequate Folic Acid Intake: Perhaps the most well-known risk factor is not getting enough folate (vitamin B₉) around the time of conception (CDC, 2024b). Folic acid is crucial for proper neural tube closure. Women who do not take prenatal vitamins or folic acid supplements and have poor dietary folate intake have a higher risk of having a baby with spina bifida. Public health measures like fortifying grains with folic acid have significantly reduced NTD rates, highlighting the importance of folate.

  • Certain Medications: Some medications can interfere with fetal development and increase spina bifida risk. Notably, certain anti-seizure drugs such as valproic acid (used for epilepsy or bipolar disorder) are known teratogens that can cause neural tube defects (MedlinePlus Genetics, n.d.). These medications may disrupt folate metabolism or gene expression during neural tube formation. Women who need antiepileptic drugs are carefully managed and often prescribed high-dose folic acid if they become pregnant. Other medications, like some acne drugs (for example, isotretinoin), are also linked to birth defects and contraindicated in pregnancy.

  • Maternal Diabetes: Pre-existing diabetes (type 1 or type 2) that is poorly controlled in the mother is associated with a higher risk of birth defects, including spina bifida (CDC, 2024b). High blood sugar levels during the critical period of neural tube development can have teratogenic effects. Good diabetes management before and during pregnancy can help reduce this risk.

  • Maternal Obesity: Women who are obese before pregnancy have an increased risk of having a baby with spina bifida—as well as some other birth defects (UCSF Benioff Children's Hospitals, n.d.). The reasons are not fully clear, but it may relate to nutritional factors or undiagnosed insulin resistance/diabetes in the mother. It’s advised that women reach a healthy weight before pregnancy if possible.

  • High Body Temperature in Early Pregnancy: Exposure of the early embryo to overheating can raise the risk of neural tube defects. For example, a high fever in the first trimester, or frequent use of hot tubs/saunas in early pregnancy, has been linked to spina bifida (CDC, 2024b; MedlinePlus Genetics, n.d.). Fever due to illness should be managed promptly in pregnant women if possible. It follows that it’s also advisable to avoid hot tub baths in the first trimester.

  • Family History and Genetic Factors: As mentioned, a family history of spina bifida or other neural tube defects increases risk. If parents have had one child with spina bifida, the chance of recurrence in a subsequent pregnancy is on the order of roughly 4% (Sebold et al., 2005), though how precise similar figures are can vary. Having a parent (especially the mother) with spina bifida also elevates the risk for the child. These familial cases suggest genetic predispositions. Additionally, certain inherited gene variants (like in folate processing genes, discussed on the next page) can make spina bifida more likely under the right conditions. Couples with a family history are often counseled to take high-dose folic acid and may undergo genetic counseling when planning a pregnancy (Spina Bifida Association, n.d.).

  • Other Factors: Some other potential influences have been reported. For instance, maternal seizure disorders themselves (independent of medication) or maternal hyperthermia as mentioned might contribute. There is ongoing research into nutritional factors beyond folate; one candidate is inositol (vitamin B₈), which in some studies helped prevent neural tube defects in lab models when folate alone was not effective. Also, maternal smoking has been explored as a possible minor risk factor for NTDs, though folate status is far more significant.

It’s crucial to understand that having one or more risk factors does not guarantee a baby will have spina bifida – it simply elevates the risk. Likewise, spina bifida can and does occur in pregnancies with no known risk factors at all. However, by managing possible risks (like taking folic acid and controlling diabetes), and with proper prenatal care, the chances of spina bifida can be reduced, while not entirely eliminated. Researchers continue to study why the neural tube fails to close in some pregnancies but not others, aiming to fully understand the impact of genes and environment behind spina bifida.