Neural tube defects
Neural tube defects (NTDs) are birth defects of the brain and spinal cord. They happen in about 3,000 pregnancies each year in the United States.
A baby’s neural tube normally develops into the brain and spinal cord. It starts out as a tiny, flat ribbon that turns into a tube by the end of the first month of pregnancy. NTDs happen if the tube doesn’t close completely. NTDs can cause serious problems for babies, including death.
If women of childbearing age take 400 micrograms of folic acid every day before and during early pregnancy, it may help reduce their baby's risk for NTDS. Folic acid is a B vitamin that every cell in your body needs for normal growth and development.
Spina bifida is the most common NTD. It affects about 1,500 babies a year in this country. In this condition, the tiny bones of the vertebrae do not close completely, and a part of the spinal cord pokes through the spine.
Spina bifida sometimes can be treated with surgery before or after birth. But children with spina bifida may have paralyzed legs and problems controlling their bladder and bowel (going to the bathroom). There also are milder forms of spina bifida that cause fewer problems for children.
Anencephaly is one of the most severe NTDs. It affects about 1,000 babies each year in this country. Babies with this condition are missing major parts of the brain, skull and scalp. They do not survive long after birth, usually for just a few hours.
Anencephaly occurs when the upper part of the neural tube that forms the brain does not close completely. Babies with this condition often have other birth defects of the head and face, as well as defects in other parts of the body.
Girls are three times more likely than boys to have anencephaly.
Encephalocele is a rare NTD that affects the brain and skull. About 375 babies are born with this NTD in the United States each year.
In this condition, a sac that contains the membranes that cover the brain pokes through an opening in the skull. Often, part of the brain pokes through, too. These conditions usually happen:
- At the base of the skull where it meets the neck (the most common site)
- Between the forehead and nose
- In middle of the upper part of the skull
Babies with encephalocele generally need surgery to place parts of the brain back inside the skull and close the opening.
Some babies have a build-up of fluid in the brain. This is called hydrocephalus. Babies with this condition are treated with surgery to insert a tube (called a shunt) into the brain. The shunt drains excess fluid. The shunt runs under the skin into the chest or abdomen, and the fluid passes into the child’s body. The fluid does not hurt other parts of the child’s body.
The outlook for children with encephalocele depends on the location of the opening, the parts of the brain that are affected, and whether or not they have other birth defects. At least half of all children with encephalocele have other birth defects, including defects of the head and face. About 20 percent are stillborn. Stillborn means that a baby dies in the womb after 20 weeks of pregnancy but before birth.
Lasting disabilities for children with encephalocele can include:
- Intellectual disabilities. These happen in about 75 percent of children with encephalocele. The remaining 25 percent may have normal intelligence.
- Movement problems or paralysis (not being able to move)
- Vision problems
What causes NTDs?
We’re not exactly sure what causes NTDs. There may be one or several causes, including:
- Genetics. This means a baby inherits the condition from his parents. Parents pass traits like eye and hair color and sometimes birth defects to their children through genes.
- Environment. This is things that you come in contact with in everyday life. Some can be harmful to a pregnancy, like air pollution, lead and cigarette smoke.
Anyone can have a baby with an NTD. But some are more likely than others:
- Couples with a family history of NTDs. This means you’ve already had a baby with an NTD or someone in your family has had a baby with an NTD. A couple with one child with an NTD has a 4 out of 100 chance (4 percent) of having another baby with an NTD. A couple with two affected children has a 1 in 10 chance (10 percent) chance of having another baby with an NTD. If you have a family history of NTDs, see a genetic counselor to discuss risks of NTDs to your future children.
- Women who take certain anti-seizure medications. If you take medicine to prevent seizures, talk to your health care provider before you get pregnant about how the medicine may affect your pregnancy.
- Women who are obese. Some studies show that being obese increases your risk for having a baby with an NTD. Talk to your provider about getting to a healthy weight before pregnancy.
- Women who have diabetes. Diabetes is a medical condition in which your body has too much sugar (called glucose) in their blood.
- Certain groups of people. In North America, Hispanics are at highest risk of having a baby with an NTD, followed by whites. NTDs are less common among Ashkenazi Jews, blacks and most Asians.
Taking the B-vitamin folic acid can help prevent NTDs. It’s important to have enough folic acid in your system before pregnancy and during early pregnancy, before the neural tube closes.
The March of Dimes recommends that all women of childbearing age take a multivitamin with at least 400 micrograms of folic acid every day before pregnancy and during early pregnancy. You can take up to 1,000 micrograms each day. But don’t take more than 1,000 micrograms unless you talk to your provider first.
You need folic acid when you’re pregnant, too. During pregnancy, take a prenatal vitamin that has at least 600 micrograms of folic acid in it every day.
If you’ve already had a pregnancy affected by an NTD, you need even more folic acid. Take at least 4,000 micrograms of folic acid each day, starting at least 1 month before pregnancy and during the first trimester of pregnancy. Studies show that taking this amount before and during early pregnancy can help reduce your risk of having another baby with an NTD by about 70 percent. Women with spina bifida, diabetes or seizure disorders also need this much folic acid every day. Talk to your provider about how to get this much folic acid.
Yes, you can get folic acid from the foods you eat. Some flour, breads, cereals and pasta have folic acid added to them. Look for the words “enriched,” “fortified” or “folic acid” on the package to know if the product has folic acid in it. Corn products, like corn tortillas and corn meal, are not fortified with folic acid now. But they may be in the future.
You also can get folic acid from some fruits and vegetables. When folic acid is naturally in a food, it’s called folate Good sources of folate are:
- Leafy green vegetables
- Orange juice
You have to eat a lot of these foods to get the right amount of folic acid every day. So even if you eat them, remember to take your vitamin, too.
Yes. Health care providers routinely offer pregnant women screening tests to help identify babies that are at increased risk of having an NTD. These screening tests include:
- Quad screen. This blood test measures four substances in a mother’s blood to tell if her pregnancy is at an increased risk of having an NTD, other than encephalocele.
- Ultrasound. This test can help detect pregnancies at increased risk of encephalocele and other NTDs.
If a screening test shows an increased risk of NTDs, your provider may recommend additional tests, such as amniocentesis and a detailed ultrasound of the baby’s skull and spine.
If an NTD is diagnosed early in pregnancy, you can talk to your health care provider to learn more about your baby’s condition and birth and treatment options. For example:
- You can plan to have your baby in a medical center that specializes in caring for babies with NTDs. This way your baby can have any necessary surgery or treatment soon after birth.
- You can talk to your provider about whether a vaginal or cesarean birth is better for your baby.
- Your baby may be able to have surgery to repair spina bifida before birth, while still in the womb. More than 400 babies have had this kind of surgery. Research shows that surgery on a baby to repair spina bifida while still in the womb is more effective than surgery after birth.
Yes. A number of researchers supported by the March of Dimes are looking for genes that may contribute to NTDs. Others are working to better understand how folic acid prevents NTDs.
American Academy of Pediatrics
Spina Bifida Association
Centers for Disease Control and Prevention
Last reviewed November 2012
See also: Your first prenatal checkup, Later prenatal checkups
Frequently Asked Questions
Can dad's exposure to chemicals harm his future kids?
Dad's exposure to harmful chemicals and substances before conception or during his partner's pregnancy can affect his children. Harmful exposures can include drugs (prescription, over-the-counter and illegal drugs), alcohol, cigarettes, cigarette smoke, chemotherapy and radiation. They also include exposure to lead, mercury and pesticides.
Unlike mom's exposures, dad's exposures do not appear to cause birth defects. They can, however, damage a man's sperm quality, causing fertility problems and miscarriage. Some exposures may cause genetic changes in sperm that may increase the risk of childhood cancer. Cancer treatments, like chemotherapy and radiation, can seriously alter sperm, at least for a few months post treatment. Some men choose to bank their sperm to preserve its integrity before they receive treatment. If you have a question about a specific exposure, contact the Organization of Teratology Information Specialists at www.otispregnancy.org.
Can Rh factor affect my baby?
The Rh factor may be a problem if mom is Rh-negative but dad is Rh-positive. If dad is Rh-negative, there is no risk.
If your baby gets her Rh-positive factor from dad, your body may believe that your baby's red blood cells are foreign elements attacking you. Your body may make antibodies to fight them. This is called sensitization.
If you're Rh-negative, you can get shots of Rh immune globulin (RhIg) to stop your body from attacking your baby. It's best to get these shots at 28 weeks of pregnancy and again within 72 hours of giving birth if a blood test shows that your baby is Rh-positive. You won't need anymore shots after giving birth if your baby is Rh-negative. You should also get a shot after certain pregnancy exams like an amniocentesis, a chorionic villus sampling or an external cephalic version (when your provider tries to turn a breech-position baby head down before labor). You'll also want to get the shot if you have a miscarriage, an ectopic pregnancy or suffer abdominal trauma.
Does cleft lip or cleft palate cause dental problems?
A cleft lip or cleft palate that extends into the upper gums (where top teeth develop) can cause your baby to have certain dental problems, including:
- Missing teeth
- Too many teeth
- Oddly shaped teeth
- Teeth that are out of position around the cleft
Every baby with a cleft lip or palate should get regular dental checkups by a dentist with experience taking care of children with oral clefts. Dental problems caused by cleft lip or palate usually can be fixed. If needed, your baby can get ongoing care by a team of experts, including:
- A dentist
- An orthodontist to move teeth using braces
- An oral surgeon to reposition parts of the upper jaw, if needed, and to fix the cleft
See also: Cleft lip and cleft palate
Does cleft lip or cleft palate cause ear problems?
Cleft lip does not cause ear problems.
Babies with cleft palate, however, are more likely than other babies to have ear infections and, in some cases, hearing loss. This is because cleft palate can cause fluid to build up in your baby’s middle ear. The fluid can become infected and cause fever and earache. If fluid keeps building up with or without infection, it can cause mild to moderate hearing loss.
Without treatment , hearing loss can affect your baby’s language development and may become permanent.
With the right care, this kind of hearing loss is usually temporary. Your baby’s provider may recommend:
- Having your baby’s ears checked regularly for fluid buildup
- Medicines for treating fluid buildup and ear infections
- Ear tubes if your baby has fluid in his ears over and over again. Ear tubes are tiny tubes that are inserted into the eardrum to drain the fluid and help prevent infections.
See also: Cleft lip and cleft palate
Does cleft lip or cleft palate cause problems with breastfeeding?
Babies with only a cleft lip usually don’t have trouble breastfeeding. Most of the time, they can breastfeed just fine. But they may need some extra time to get started.
Babies with cleft lip and palate or with isolated cleft palate can have:
- Trouble sucking strong enough to draw milk through a nipple
- Problems with gagging or choking
- Problems with milk coming through the nose while feeding
Most babies with cleft palate can’t feed from the breast. If your baby has cleft palate, he can still get the health benefits of breastfeeding if you feed him breast milk from a bottle. Your provider can show you how to express (pump) milk from your breasts and store breast milk.
Your baby’s provider can help you start good breastfeeding habits right after your baby is born. She may recommend:
- Special nipples and bottles that can make feeding breast milk from a bottle easier
- An obturator. This is a small plastic plate that fits into the roof of your baby’s mouth and covers the cleft opening during feeding.
See also: Cleft lip and cleft palate, Breastfeeding
Does cleft lip or cleft palate cause speech problems?
Children with cleft lip generally have normal speech. Children with cleft lip and palate or isolated cleft palate may:
- Develop speech more slowly
- Have a nasal sound when speaking
- Have trouble making certain sounds
Most children can develop normal speech after having cleft palate repair. However, some children may need speech therapy to help develop normal speech.
See also: Cleft lip and cleft palate
What are choroid plexus cysts?
The choroid plexus is the area of the brain that produces the fluid that surrounds the brain and spinal cord. This is not an area of the brain that involves learning or thinking. Occasionally, one or more cysts can form in the choroid plexus. These cysts are made of blood vessels and tissue. They do not cause intellectual disabilities or learning problems. Using ultrasound, a health care provider can see these cysts in about 1 in 120 pregnancies at 15 to 20 weeks gestation. Most disappear during pregnancy or within several months after birth and are no risk to the baby. They aren't a problem by themselves. But if screening tests show other signs of risk, they may indicate a possible genetic defect. In this case, testing with higher-level ultrasound and/or amniocentesis may be recommended to confirm or rule out serious problems.
What if I didn't take folic acid before pregnancy?
If you didn’t take folic acid before getting pregnant, it doesn't necessarily mean that your baby will be born with birth defects. If women of childbearing age take 400 micrograms of folic acid every day before and during early pregnancy, it may help reduce their baby’s risk for birth defects of the brain and spin called neural tube defects (NTDs). But it only works if you take it before getting pregnant and during the first few weeks of pregnancy, often before you may even know you’re pregnant.
Because nearly half of all pregnancies in the United States are unplanned, it's important that all women of childbearing age (even if they're not trying to get pregnant) get at least 400 micrograms of folic acid every day. Take a multivitamin with folic acid before pregnancy. During pregnancy, switch to a prenatal vitamin, which should have 600 micrograms of folic acid.
Last reviewed November 2012