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NIH MedlinePlus the Magazine, Trusted Health Information from the National Institutes of Health

Understanding Prenatal Tests

A pregnant woman.

Prior to the birth of your baby, your health care professional may recommend one or more of the following tests. Ask your health care professional if any of these tests are right for you:

Amniocentesis This test takes a small sample of the amniotic fluid surrounding the baby. This test can be given after 14 weeks or during the third trimester. The former checks for genetic defects like Downs Syndrome; the latter checks for abnormal lung development.
Chorionic Villus Sampling (CVS) This test withdraws a small sample of tissue from just outside the amniotic sac in which the baby grows. Taken between 10 and 12 weeks, this test checks for the possibility of such genetic diseases as Huntington's Disease and Duchenne muscular dystrophy.
Quad-Screen Test This is a blood test taken from the mother that checks several different components. This test is usually performed in the second trimester (15-20 weeks). The screening looks for several things, particularly the risk of Down Syndrome.
Rh Incompatibility This test determines whether the mother and baby have incompatible blood types. This test can be done before pregnancy or at the first prenatal visit. If there is Rh incompatibility, treatments can help prevent later complications.
Ultrasound This test uses highfrequency sound waves to show internal organs and the growing baby within the womb. Ultrasound can be used during the first, second, and third trimesters to show the gender, status, position, health, and growth of the baby.

Photo: iStock

Winter 2008 Issue: Volume 3 Number 1 Page 22