Neural Tube Defect

By Lalaine Mortera, MD

Neural tube defect (NTD) is found in about one in 1,000 liveborn babies, making it a relatively common birth defect. It is a group of birth defects that results from failure of the brain and spine to develop properly. Anencephaly is a fatal condition in which most of the brain is absent. Spina bifida, the most common of the neural tube defects, occurs when the spine fails to close properly. Because of the advances of medical and surgical care, most of the babies born with spina bifida survive.

Depending on the severity of the condition, patients with NTDs have problems with varying degrees of paralysis, loss of sensation especially in the lower limbs, difficulties with bowel and bladder control, hydrocephalus or fluid in the brain, learning disabilities, and latex allergies.

A combination of varied genetic and environmental factors play a role in the development of neural tube defects. A woman who has already had a baby born with NTDs is more likely to have another affected pregnancy. It is found to be increased in the British Isles and Ireland, and more frequent in Caucasians than Blacks and Orientals. These differences persist even after migration, suggesting a genetic influence. Mothers who are taking anti-seizure medications such as valporic acid or carbamazepine also have a higher risk of having a child born with NTDs. You need to ask your physician about this prior to discontinuation of these medications. Ongoing research about the role of other factors helps us find solutions in decreasing the incidence of this devastating condition.

To decrease the chances of having a baby born with NTDs, it is currently recommended that women of childbearing age (15 to 45 years of age) who are capable of getting pregnant take folic acid daily, at least three months prior to getting pregnant and up to at least one month after conceiving.

Remember that NTDs occur within the first month of pregnancy, when one is not yet aware of the pregnancy. It may be too late to take folic acid after getting pregnant.

The Food and Drug Administration (FDA) had ordered fortification of all food grains with folic acid in an attempt to increase the amount of folic acid availability and decrease the incidence of NTDs. Foods that are rich in folate include fresh dark leafy green vegetables (e.g. broccoli, spinach), asparagus, some nuts and seeds, dried beans, wheat germ, egg yolks, yeast, liver, kidney, certain fresh fruits and fruit juices.

One should not depend on food and fortified grains alone because it is not enough. Taking a vitamin pill daily that contains at least 0.4 milligrams (mg) or 400 micrograms (mcg) is the only way to be certain of receiving enough folic acid. Women who have had a previous pregnancy with NTDs should take a much higher amount of folic acid that may be prescribed by your physician.

Remember, NTDs are common birth defects that are at times preventable. Consider seeing your physician for advise.

Literature and information are also available through the Spina Bifida Association of America (SBAA) and the March of Dimes/Birth Defects Foundation.

Dr Mortera is a pediatrician at Newtown Pediatrics and a specialist in genetics.