Neural tube defects (NTDs) are birth defects of the brain, spine or spinal cord that happen in fetuses within the first month of pregnancy. NTDs are linked to folate (folic acid) deficiency before and during pregnancy, so it’s important to make sure you’re getting enough folate through supplements and in your diet before and during pregnancy.
Neural tube defects (NTDs) are birth defects (congenital conditions) of the brain, spine or spinal cord. They happen to developing fetuses within the first month of pregnancy — often before you even know you’re pregnant. The two most common neural tube defects are spina bifida and anencephaly.
Normally, during your first month of pregnancy, the two sides of the fetus's spine (backbone) join together to cover and protect the spinal cord, spinal nerves and meninges (the tissues covering the spinal cord). At this point, the developing brain and spine are called the neural tube.
As development progresses, the top of the neural tube becomes the brain, and the rest of the tube becomes the spinal cord. An NTD happens when this tube doesn’t close completely somewhere along its length.
There are several types of neural tube defects, including:
Spina bifida is the most common type of neural tube defect (NTD). It happens when the neural tube doesn’t close completely somewhere along the spine during fetal development.
There are a few different types of spina bifida, including:
Anencephaly happens when the fetus's neural tube doesn’t close at the top during fetal development. This causes the skull, scalp and brain not to develop properly, and portions of the brain and skull are missing. The brain tissue that does form is usually exposed because there isn’t enough skin and bone to cover it. Infants with anencephaly are either stillborn or die soon after birth.
Encephalocele happens when the neural tube doesn’t close near the brain, and there’s an opening in the skull. The fetus's brain and the membranes that cover it can protrude through the skull, forming a sac-like bulge. In some cases, there’s only a small opening in the nasal cavity or forehead area that’s not noticeable.
Iniencephaly happens when the spine is severely malformed (misshapen). It often causes a lack of a neck, and your baby’s head is bent severely backward. The skin of your baby’s face is connected to their chest, and their scalp is connected to their back. Babies with iniencephaly are usually stillborn.
Neural tube defects (NTDs) are birth defects (congenital conditions), so they develop in fetuses. NTDs develop within the first month of pregnancy.
Neural tube defects (NTDs) occur in about 3,000 pregnancies each year in the United States. To put that into perspective, there were approximately 3,605,000 births in the U.S. in 2020.
The two most common NTDs are spina bifida and anencephaly. Spina bifida affects about 1,500 babies a year in the U.S., with myelomeningocele being the most common form. Anencephaly affects about 1,000 babies each year in the U.S.
Encephalocele and iniencephaly are both rare NTDs.
Healthcare providers and scientists don’t yet know the exact cause of neural tube defects (NTDs), but they believe it’s a complex combination of genetic, nutritional and environmental factors.
In particular, low levels of folic acid in a person’s body before and during early pregnancy appear to play a part in this type of congenital condition. Folic acid (or folate) is important for the fetal development of the brain and spinal cord.
Each type of neural tube defect (NTD) has different symptoms.
Some babies with NTDs have no symptoms, while others experience serious disabilities. Babies with iniencephaly and anencephaly are typically stillborn or die shortly after birth due to complications from the defect.
General symptoms of NTDs can include:
If your healthcare provider suspects that the fetus you're carrying has a neural tube defect, your medical team will be able to provide more information about what to expect. NTDs affect each baby differently.
If you’re pregnant with a fetus that has a neural tube defect (NTD), you won’t experience any symptoms directly related to it.
When you undergo a fetal ultrasound, your healthcare provider will look for certain signs of the fetus's health and development depending on its fetal age, including looking for signs of NTDs in the spine and head. Healthcare providers can usually diagnose NTDs with an ultrasound.
Healthcare providers typically diagnose neural tube defects (NTDs) during pregnancy through prenatal tests, such as ultrasound.
Healthcare providers use the following tests to help diagnose neural tube defects (NTDs) before birth:
There are several treatment options for spina bifida and encephalocele depending on the severity of the condition.
There isn’t a treatment for anencephaly or iniencephaly. Infants with these conditions are typically stillborn or die shortly after birth.
Treatment for both spina bifida and encephalocele depends on the severity of the condition and if your baby has other complications. Surgery is a common option for both conditions.
Healthcare providers typically treat encephalocele with surgery to place the protruding part of your baby’s brain and the membranes covering it back into their skull. They then close the opening in your baby’s skull.
Treatment for myelomeningocele, the most common form of spina bifida, typically involves surgery to repair the opening in your baby’s spine. Healthcare providers can perform surgery before birth (fetal surgery) or shortly after birth (postnatal surgery).
Long-term treatment for both conditions depends on your child’s condition. They may need multiple surgeries over time and other treatments related to complications, such as a shunt to treat hydrocephalus (excess fluid surrounding their brain).
Any person can have a baby with a neural tube defect (NTD). But certain factors make you more likely to have a baby with an NTD, including:
Yes, your baby can live with certain neural tube defects, including spina bifida and encephalocele.
Babies with anencephaly and iniencephaly are typically stillborn or die shortly after birth, however.
For babies with spina bifida, especially myelomeningocele, or encephalocele, there’s a high likelihood of nerve damage, which can cause paralysis and other issues. The nerve damage and loss of function that are present at birth are usually permanent. But there are a number of treatments that can sometimes prevent further damage and help with complications.
Some babies with spina bifida have no or minimal complications.
It’s important to remember that no two people with a neural tube defect (NTD), especially spina bifida and encephalocele, are affected in the same way. It’s impossible to predict how your baby will be affected. The best way you can prepare is to talk to healthcare providers who specialize in researching and treating your baby’s condition.
As they grow, your child may benefit from a team of healthcare providers who can care for their needs. It’s important to advocate for your child and to arrange the best medical care possible.
If your child was born with a neural tube defect (NTD), they’ll likely need to see their healthcare provider — or team of healthcare providers — regularly throughout their life.
If you take antiseizure medication or opioids, it’s important to talk to your healthcare provider before becoming pregnant about how these medications could affect your pregnancy and the likelihood of having a child with an NTD.
A note from Cleveland Clinic
Learning that the fetus you're carrying has a neural tube defect (NTD) is scary and overwhelming. But know that you’re not alone — many resources are available to help you and your family. It’s important that you speak with a healthcare provider who’s very familiar with neural tube defects so you can learn more about how your baby will be affected and how to prepare.
Last reviewed by a Cleveland Clinic medical professional on 03/30/2022.
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