SPINA BIFIDA AND FOLIC ACID

September 2002
		Ask the doctors: What every woman should know about spina bifida and folic acid. Responses submitted by: Richard P. Leavitt, Director of Science Information at the National March of Dimes Foundation; Dr. Godfrey Oakley, a visiting professor of epidemiology at the Rollins School of Public Health at Emory University; and Dr. Victor Klein of the North Shore University Hospital in New York.

Forum Main What can a prospective parent with spina bifida do to avoid passing it to a child? What is spina bifida occulta? What are the risks and odds of having an anencephalic baby? A mother who took folic acid asks why her baby still had spina bifida.     Online Focus: Folic Acid-- Preparing for a Healthy Pregnancy Browse the NewsHour's coverage of health	Andrew Davis of Marietta, Georgia asks: I was born with spina bifida in 1968 at Emory. If I were interested in getting married and having a child, what are the risks that the baby will also be born with spina bifida and what test are there that can determine if the baby will get the same birth defect?" Dr. Godfrey Oakley responds: The risk that you would have a child with a neural tube defect is elevated above that found in the general population, but we do not know why. It is generally thought that the risk would be in the 1 to 5 percent range. Once a partner is pregnant there is the alpha-feto protein test and ultrasonography that can help evaluate the fetus. Medical knowledge changes all the time so it would be good you and your partner to visit a genetic specialist in birth defects such as Dr. Paul Fernhoff of Emory University to have a pre-pregnancy discussion. Of course, your partner, like all women of reproductive age, should consume 400 micrograms of synthetic folic acid a day. Dr. Victor Klein responds: The risk of having a baby with spina bifida is 2-3 percent. It is well established that taking folic acid prior to pregnancy as well as in the first trimester will decrease spina bifida in the general population by 70 percent. Patients who are at increased risk, such as yourself, should take a total of 4.0 mg of folic acid in the form of a prenatal vitamin and 3 additional 1 mg tablets of folic acid. This would decrease the chance a great deal. A detailed sonography and maternal blood tests for AFP can usually diagnose this by 16 weeks of pregnancy. Richard Leavitt responds: Spina bifida usually is an isolated birth defect. Although scientists believe that genetic and environmental factors may act together to cause this and other NTD's, 95 percent of babies with spina bifida and other NTD's are born to parents with no family history of these disorders. While spina bifida appears to run in certain families, it does not follow any particular pattern of inheritance. If one child has spina bifida, the risk of recurrence in any subsequent pregnancy is greatly increased, to about one in 40. If there are two affected children, the risk in any subsequent pregnancy is about one in 20. Spina bifida also can occur as part of a syndrome with other birth defects. Here, inheritance patterns may differ from those of isolated spina bifida. Each child of a prospective parent with spina bifida has a 1 percent to 5 percent risk of having spina bifida or, less likely, anencephaly (an early fatal NTD of the brain). Risks of spina bifida for siblings -- and presumably for offspring -- of affected individuals are reduced by up to 70 percent if the prospective mother takes 4 mg of folic acid daily, starting at least a month before conception and continuing through the first month or two of pregnancy. That is 10 times the usual preventive daily dose and requires a prescription for high-dose pills. You may be interested in consulting a genetic counselor. Genetic counseling translates scientific knowledge into practical information. A genetic counselor works with a person or family that may be at risk for inherited disease or an abnormal pregnancy outcome, discussing their chances of having children who are affected. Spina bifida often can be detected before birth using two or more tests. Most health care providers now routinely offer pregnant women a blood test called the maternal serum alpha-fetoprotein (MSAFP) screening test (part of the "triple screen"). This test detects pregnancies at higher-than-average risk of spina bifida and other NTD's, as well as certain other birth defects, including Down syndrome. If a woman has a high MSAFP test result not caused by factors such as a miscalculation of fetal age, her health care provider probably will recommend two additional tests that are accurate in detecting severe spina bifida. These are a detailed ultrasound examination of the fetal spine, and amniocentesis to measure levels of alpha fetoprotein (AFP) in amniotic fluid. Response taken directly from the March of Dimes fact sheet and the MOD Genetic Counseling booklet.