One out of every 1,000 babies in the U.S. is born with a neural tube defect (NTD). NTDs include spina bifida (open spine deformity) and anencephaly (absent skull). Spina bifida may affect the ability to walk and can cause other medical problems which may be disabling. Folic acid supplementation prior to conception and throughout the first trimester has been shown to reduce the risk for NTDs. All women of reproductive age should consume 400 micrograms of folic acid daily.
Why should I consider having this test?
Measuring the alpha-fetoprotein (AFP) level by a blood test checks for open NTDs. About 80 percent of the time when a woman is carrying a child with spina bifida or anencephaly, her blood test will show a higher than normal AFP level.
Should I have this test if there has never been anyone in our families with spina bifida or anencephaly?
Yes. In 90 to 95 percent of the cases in which a child is born with spina bifida or anencephaly, there has never been anyone else in the family with this problem.
What if my partner or I have a relative with spina bifida or anencephaly?
A family history of spina bifida, anencephaly or other spinal cord problems may indicate a higher than expected risk. Our genetic counselors can help determine what your risk is and what type of test would be best for your situation.
If my blood test shows a high level of AFP, does that mean that my child will have spina bifida or anencephaly?
No, not necessarily. There are many other reasons why the AFP level may be higher than normal in a woman’s blood. In fact, most women with a higher than expected level of AFP will have normal babies. An ultrasound often explains why the AFP level is high. For example, pregnancy may be further along than realized, or the woman may be carrying twins. Ultrasound can detect about 90 percent of neural tube defects.
What if my blood test shows a high level of AFP and the ultrasound does not show a reason for this: does this mean spina bifida?
No, not necessarily. Once again, most women in this situation have normal pregnancies. However, amniocentesis may be suggested to measure AFP in the amniotic fluid since this is a very accurate way to determine if the fetus has spina bifida. Patients with elevated blood AFP levels that are unexplained have an increased risk for complications later in pregnancy and are watched more carefully by their doctors in the third trimester.
What if you find that my baby has spina bifida or some other birth defect?
In cases such as this, our genetics staff will help explain the results of the test as well as discuss all possible options with you, including delivery and raising a child with special needs.