High-Risk Tests Performed During Pregnancy

That first delightful glow that often comes in the early stages of pregnancy can end very quickly when the new mom is bombarded with information and decisions that need to be made to encourage a safe pregnancy and the birth of a healthy child.

Every newly expectant mom begins to wonder if invasive tests are really necessary, especially those that might put the health of the infant at risk in some way. Wading through the sea of information, however, is not for the weak. All expectant mothers need to arm themselves with information, work cooperatively with their health care providers, and, like a two year old, never stop asking questions. The following high-risk tests may be medically necessary, particularly for older moms or those with chronic health conditions or a family history of genetic disorders, but they require careful consideration:

Down Syndrome Screen

This test, usually performed between the eleventh and fourteenth week of pregnancy, requires that a blood sample be taken from the mother and augments this information with ultrasound imaging to assess whether a fetus is at risk of chromosomal abnormalities that might result in Down syndrome. The ultrasound gives doctors the ability to measure the amount of fluid in the tissues at the back of the infant’s neck, while the blood test detects abnormal levels of a specific protein and hormone that are associated with Down syndrome.

Triple or Quad Marker Screen

Between the fifteenth and twentieth week of pregnancy, doctors can perform a blood test on the mother to determine if the fetus is likely to have neural tube defects or other chromosomal irregularities. These screens can determine the risks for spina bifida, anencephaly, Edward syndrome, and Down’s syndrome. For the most part, they pose no risk to the mother or fetus, but they do sometimes require the parents to make difficult choices.

Chorionic Villus Sampling

During this test, cells are taken from the placenta during the tenth to twelfth week of pregnancy to test for abnormalities in the chromosomes of the fetus. Conditions that may be detected through chorionic villus sampling include cystic fibrosis and Tay-Sachs disease. This invasive procedure carries a one in one hundred risk of miscarriage and could also result in infection, cramping, or Rh sensitization.


During this procedure, ambiotic fluid is taken from the uterus of the mother somewhere between fifteen and twenty weeks to check for several different types of birth defects in the fetus. These include spina bifida and Down syndrome. Amniocentesis can also be used later in pregnancy, after the thirty-second week, to determine if the fetal lung development has progressed to the point that delivery is viable. Some of the risks associated with amniocentesis include leaking amniotic fluid, infection, and miscarriage.


This test requires the doctor to take a sample of fetal blood from a vein located in the umbilical cord. It is performed during the eighteenth to twenty-second week of pregnancy and is used to detect blood problems, abnormal chromosomes, and some infections. This test is so risky that it is used as a last resort to save the infant’s life. The results are available within a few days, and this procedure can be used to provide medication or blood directly to the fetus within the womb.Cordocentesis increases the risk of miscarriage to two in one hundred and can also cause a slowing of the fetal heart rate.

It is normal to feel jittery when a doctor suggests a high-risk pregnancy test, but these tests can be extremely useful. The ultimate goal is to keep both mother and child as healthy as possible during pregnancy and delivery.

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