Testing for Birth Defects
Many women undergo tests during pregnancy to check for birth defects, genetic disorders, and other problems. A few of the most common tests are ultrasound scans, the alpha- fetoprotein (AFP) test, amniocentesis, and chorionic villi sampling (CVS). Each of these can be helpful in diagnosing problems. The tests are not necessary for every pregnancy. Check with your doctor about what tests are appropriate for you.
Ultrasound -- Ultrasound technology uses high-frequency sound waves to form pictures of the fetus on a computer screen. The test can verify a due date, determine causes of bleeding, check the overall health, development, sex and position of the baby, measure the amniotic fluid, and check the condition of the placenta. There are no known risks from the tests, and many women have one or two ultrasounds in routine pregnancies. There is little scientific evidence that normal pregnancies benefit from ultrasound tests.
Alpha-fetoprotein Screening (AFP) -- A simple blood
test that poses no risk to the fetus, AFP screening
measures the levels of alpha-fetoprotein in the mother's
blood. Abnormal levels can indicate a brain or spinal cord
defect, the presence of twins, a miscalculated due date, or
an increased risk of Down syndrome. Since AFP
levels can be elevated for a number of reasons, a positive
test is usually repeated or followed up by other tests
before a diagnosis is made. Very few women with elevated
AFP levels are found later to have babies with birth