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Inherited Disorders and Birth Defects

84% chance/ spinal bifida due date 02/17/?

10/10/2007

Question:

What can be done at this time of pregnancy, to lower chance of a 84% chance of spina bifida due date 03/07/08 based on blood test, the visual viewing of baby looked perfect. I have been taking prenatal vitamins with folic acid since Aug 1st when I found out I was pregnant. I have 2 boys 3-1/2 and 4-1/2 that are fine. I have always taken multivitamins several times per week and garlic and vita C etc. I am 36 and somewhat overweight, the doctor said I had a body of a teenager before his office called me in to consult about an additional blood test. Can I take extra folic acid. please give me some possible recommendations or tell me if I should be overly concerned. Also, are there risk in invasive fluid removal testing for spina bifida.

Answer:

From your description, I am assuming you had a maternal serum screen to look for chromosome abnormalities (like Down syndrome) as well as to look for birth defects such as spina bifida (also called a neural tube defect). The screening test looks at 3 types of biochemical products that have been found to be associated with chromosome problems and spina bifida. This blood test is a screening test, not a diagnostic test - it can only tell you about your potential chance or risk to have a baby with spina bifida. It cannot tell you for sure if the baby will have spina bifida.

Usually there are 2 tests that people will have to follow-up after the screening results - an ultrasound to look for abnormalities of the spine and other birth defects - which you said was normal. The other test is an amniocentesis (using a thin needle to draw out some of the fluid that surrounds the baby) during the second trimester to see if there are increased levels of alpha-feto protein in the fluid surrounding the baby.

However, you are correct; there is a chance of complications that can lead to a miscarriage following amniocentesis. Doctors usually say the risk is about a half of a percent (0.5% or 1 in 200), but a recent study suggests that the risk of miscarriage may be less than this, about 0.06% or 1 in 1600 pregnancies.

Research has shown that a major proportion of neural tube defects, including spina bifida, can be prevented if women take in enough folic acid. Because neural tube defects close so early in pregnancy, the March of Dimes recommends that "women take a multivitamin containing 400 micrograms of folic acid daily, and eat a healthy diet including foods rich in folic acid. This is the most reliable way of ensuring that a woman gets all the folic acid she needs." It appears that you have been taking a multivitamin, which you should continue to do. However, you should not take any more than the recommended amount as this could be toxic.

I would recommend that you ask your doctor about a referral to talk to a genetic counselor or geneticist to discuss these issues in depth. This is an area that they have a lot of expertise. You can locate a genetics center near you through the National Society of Genetic Counselors Resource Center website below.

Related Resources:

National Society of Genetic Counselors Resource Center

For more information:

Go to the Inherited Disorders and Birth Defects health topic, where you can:

Response by:

Anne   Matthews, RN, PhD Anne Matthews, RN, PhD
Associate Professor of Genetics
School of Medicine
Case Western Reserve University